AR Build - Moved from Biopar Site

[gitano]

When I thought THL might be 'down for the count', I started posting threads at the Biopar.com website. Since THL has had new life breathed into it, at least for the near future, I decided to move this thread here to THL. There are a couple of active threads that refer to this (AR-15) rifle, as well as the AR-10 build. I will move that thread here as well. I can't move the posts made by others and have them actually be "from" them, but I reference them appropriately. Here's how it starts:


I've never been too interested in semi-auto firearms be they pistols, rifles, or shotguns. I don't dis-like them, I'm just not 'turned on' by them. That said, I do own semi-auto pistols, rifles, and shotguns. However, the semi-auto rifles I own are only those I have obtained for my military surplus collection.

Of late, suppressed subsonic cartridges have been occupying a lot of my thoughts simply in the context of the ballistics associated with delivering lethal energy to a game animal at 100yd and less. When one considers the constraints put upon a firearm by forcing subsonic muzzle velocities, the AR platform moves quickly to "the short list" of firearms to consider as one on which to build a purpose-specific rifle.

What I didn't know about ARs - the .223 Rem/5.56 NATO AR-15 and the .308 Win/7.62 NATO AR-10 - filled volumes. I knew they were "modular", but I had NO IDEA just HOW modular they actually are. It is an absolutely true statement that a "Regular Joe" can buy ALL of the COMPONENT parts of an AR in the mail - with lower receiver transferred through an FFL - and assemble a fully functional semi-auto rifle in his basement. And by "components" I don't mean some big assemblies like a fully operational "upper" and a fully operational "lower". I mean ELEMENTAL component - no smaller piece. I do in fact believe that the possible variations are, for practical purposes, infinite.

Actually, the reason I got "into" this is because I was looking for a cartridge to chamber the barrel on this project http://thehunterslife.com/forums/showthread.php?t=15825. My search led me to the 7.92x33 Kurz. http://en.wikipedia.org/wiki/7.92%C3%9733mm_Kurz Some time ago, Paul Hoskins sent me a spiffy little 8mm mould that throws a gas-checked 189-grain spitzer bullet. It looks really good in that Kurz case. As I looked at it, it occurred to me that it would be an excellent cartridge for an AR. So the quest commenced.

I got on the //www.AR15.com site, and started asking around if anyone knew of where I might get an 8mm barrel for an AR. (See here http://www.ar15.com/forums/t_3_4/561255_8mm_AR_Barrels.html and here http://www.ar15.com/forums/t_3_121/561468_8mm_AR_Barrels_and_Other_7_92x33_Kurz_Case_specific_Questions.html for the major part of my preliminary education.)

The 'bottom line' is that I dove in head first, or as joe_bl0ggs would say, I "filled my boots and got on with it". Here's what "drove me over the edge": A company called Tactical Machining https://www.tacticalmachining.com/ sells a product it calls an "80% receiver". The machine work on this receiver is not complete - about 20% left to do - and therefore it is NOT a "firearm" by BATFE sanction. Tactical Machining has the documentation from the BATFE asserting their "determination" that the product being sold is NOT a "firearm". Therefore, there is no need to transfer ownership through an FFL.

My interest is NOT in sidestepping the FFL transfer. That's just a major inconvenience for me. I have to drive 120 miles RT to get a guy to charge me to handle my receiver. More important to me though, is the opportunity to truly BUILD my own rifle. I have the mill necessary to do the work properly, and the machining skills required are within my skill set. I promptly ordered the kit from Tactical Machining. The kit contains one 80% AR-15 receiver, one 80% AR-10 receiver, and the jigs for each. I got them yesterday. I am pumped! This is going to be REALLY FUN! I'll walk through the whole process, with pictures, in this thread.

For a start, here's what I have in hand:

The kit in total.


There are the two 80% receivers. The one on the right is the AR-10 and has its jig attached. The jig consists of 4 parts:

1) Left and right sides, (plates "A" and "B"), that index to the receiver and have holes for the trigger, hammer, and shot selector.
2) The "Master" plate that holds a template for the "fire control group" (trigger assembly) cavity.
3) The above-mentioned template.

In addition to the AR-10 receiver with jig attached, you can see the AR-15 80% receiver, two of the three template plates, and the two side plates for the AR-15 receiver.

Here is a look at the receivers from the top:


and two from the bottom:




Here are some side shots:




Here is from the front:


and here from the butt:


And here is a sequence of putting hte side-plates on the AR-15 80% receiver:
Both plates alongside:


Plate A on:


Both plates on and looking from the top.


I would urge you to have a read through this thread http://www.tacticalmachining.com/forum/viewtopic.php?f=10&t=11 to get a more complete idea about this project. I will not be anodizing, and probably not etching, mine, but I will be doing all of the machining parts. I'll take pictures of my personal progress as I do the machining.

At the moment, I am waiting on the "lower" parts kit from Midway http://www.midwayusa.com/product/877204/dpms-lower-receiver-parts-kit-ar-15 and some specif end mills from eBay before I start the mill work. Well actually, I will drill the trigger, hammer, and shot selection holes before I get the parts kit and mills, but that will be the end of the work until I get the lower parts kit.

More to come. Wait 'til you see the sexy way they rigged the breech of the barrel.

Paul

[gitano]

By drinksgin

Oh ,boy!
This is likely to be the the most fun you can do with your clothes on!


nra, tsra, goa, 2nd amm. jpfo, def con.

[gitano]

By Nelsdau

Interesting ideas there Paul. I think the Kurz needs a longer neck and sharper shoulders, like a 30BR. Since I know nothing about ARs it will be thrilling to be a spectator on your work and interesting where you find the limitations to be.

Nels

[gitano]

By Jorge in OZ

Paul, very interesting so far can't wait for the next instalments.

Can't wait to see those babies together.

Love the 8mms.

Cheers

Jorge
“The Germans brought the best hunting rifle to the war. The Americans brought the best target rifle. The British brought the best battle rifle!”



"Law and order break down as a direct result of placing political correctness above equity and truth" Mark Jenkins

[gitano]

By j0e_bl0ggs

Poor ol' beggar has been drooling about this for weeks... finally he hit the buy it now button!!!

Cooooool!


Wolfie better watch out now...BigGrin

[gitano]

Thanks folks.

My friend Grant - the fellow with the cabin at Skwentna - is also keenly interested 'joining the fray' of building his own AR-15. Actually, I'm a bit surprised at the level of his interest. He wants one in .338 Whisper MK1 (the one built on the .223 case, not the 7mm BR case). We're going to get together this afternoon, (after he gets back from a snowmachine-based freight run of sheetrock out to the cabin), and discuss the 'details' of getting him a lower receiver kit from Tactical Machine.

I've been thinking about A&B barrels. Unchambered, they can be had from Midway for $90 +S&H in most popular calibers including .338. It bugs me that I have to waste 8" of a 24" barrel though. (That's considering the minimum legal barrel length (without the "short-barreled-rifle" SBR permit required for a barrel shorter than 16".) For subsonic applications, there's no reason to make barrels longer than 16". So... I think I may have to get an SBR permit just so I can make use of the 8" 'stub' left over from making a 16" AR barrel. I'm beginning to understand the fascination with the AR platform.

As j0e_bl0ggs said, I "hit the BUY button" on a couple of more pieces. I checked out the prices, including shipping, for "parting" the upper receiver. I didn't even get to the end before it was more expensive than this one: http://www.midwayusa.com...glacierguard-handguard. I will certainly 'throw away' the handquard, and maybe (maybe not) the barrel, but this will ease the angst of trying to make sure I am getting all the RIGHT parts for this first build. I also ordered a lower receiver parts kit http://www.midwayusa.com...ceiver-parts-kit-ar-15, a butt stock kit: http://www.midwayusa.com...r-15-a2-synthetic-black and another .223 barrel (because it has 1:8 twist, "heavy" contour, and 18") http://www.midwayusa.com...ss-steel-black-pre-ban. Now I have to find a different handguard. Rockinbbar emphasized that a "floating" handquard is a must for the best precision.

I'm going to get the holes drilled in the receiver this afternoon, and I will TRY to get some pictures of that.

Paul

[gitano]

By RatherBHuntin

Looks interesting and more than I would be able to handle, but the premise is definitely appealing. I like the idea.

[gitano]

By 22hornet

Incredible! Because we can't do this in OZ I never really thought of it as an option.
This truly is a custom build. I for one will be watching to see the progress.

[gitano]

Two-and-a-half hours later...

"Filled my boots" and got after drilling the shot selector, trigger, and hammer holes. The jig is essentially mandatory. It would be VERY difficult without the jig. Took me about 45 minutes to get the setup leveled in the vice. There was a bit of swearing associated with that operation, but in the end I had it 0.003" from "top to bottom" (about 3" making it about 1 part in 1000) and 0.005" from end-to-end (about 7 inches or about 1 part in 1400). Since the width of the receiver is about 1", I could have been about 0.001" out of alignment top-to-bottom and about 0.0007" out fore-to-aft. That's well within specs.

The shot selector hole is 3/8ths and the trigger and hammer holes are 5/16ths. I decided to drill the 3/8ths hole first. I was advised to "peck" at it, drilling only a small amount at a time, cleaning chips and keeping it well-lubed. So that's what I did. I think it took me at least half an hour per hole.

I said I'd take pictures if I could, so I did. Here's they are. If you think of something that I haven't shown, let me know because I have the other receiver to do and I can photograph that 'next time'.

Here's the setup after leveling and with the 3/8th drill bit ready to drill:


It wasn't difficult to align the drill with the hole, but it did require careful setup as the tolerances are VERY tight on these holes.

Well-lubed remember...


Here's a picture after the first few "ins and outs":


It's tough to clear chips with the air gun and catch it with the camera. This is as close as I got:


"After a while":


On the last hole:


I'm trying to show the "comes-outta" side, but it ain't too great:

and


Here's the 'carnage' when I took the jig off:


I'm trying to show all the swarf inside the jig that was blown around by the air gun.


Here's the "off side". There was a small ridge, but it was easily dealt with using a case mouth chamfering tool.


In these next two pictures I'm trying to show that the "off-side" of the jig has not been hit with the drills:




And that's about it.

Here's the stupid thing I did... If you were looking at the names of the picture files, you'll note that they all prefixed with "AR-10". I was planning to do the AR-15 first because that is the one I am building first. However, I had the jig on the AR-10 action for all of the other pictures, and I forgot to take it off and put it in the AR-15 receiver. I'm hoping that's the biggest mistake I make on this project.

Paul

[gitano]

By j0e_bl0ggs

Well.....

They both need holes a drilling Shhh

Wish I could keep my mill as shiny as that Whistle

"Shhh" and "Whistle" emoticons from Biopar.com don't "copy".

[gitano]

Just use it as little as I use mine...

Paul

[gitano]

From BH51

Hmmmnnn......You're in well over my head but it's all most interesting.
..........Will continue to follow your progress..................BH51..

[gitano]

I finished milling the AR-15 receiver. The first time one does something one usually learns what they won't do next time. I won't use the jig for anything but layout and initial "outline" cuts. It's 'nice', but it: 1) REALLY got in my way, 2) made viewing what I was doing much more difficult, and 3) made "long" - and therefore "bendier" - mill cutters necessary. The combination of not being able to see AND long cutters really messed up what was going to be a very nice job. Literally the last cut, and the trigger hole got 'buggered' because the long, thin, mill cutter "walked". When I mill the AR-10 receiver, I will use the trigger hole plate ONLY to mark the ends, then I will mill the rest from the bottom of the receiver. I really DON'T like the arrangement of the trigger plate jig.

I didn't bring my camera into the shop while I was doing this - maybe I will when I do the AR-10 - but here are a couple of pictures of the buggered trigger hole. I am going to try to clean it up with a small - maybe 1/8th" - mill cutter. REALLY ticks me off.

Here's a shot of the cavity:


Here's the buggered trigger hole.


Paul

[gitano]

From drinksgin

I see I am not the only person with "last cut itis"!!!!!
The receiver pieces are aluminum, or some alloy of it, do you know what grade it is?
I would like to get a similar project going, but I would like a single shot action similar to the rb or 1885.
My whisper round would be the .500 S&W with a LONG cast bullet, or possibly the .357 max. with a fast twist barrel and a 350 gr. or so cast 3r bullet.
nra, tsra, goa, 2nd amm. jpfo, def con.

[gitano]

Don - The aluminum in these receivers is T7075 - "aircraft" aluminum.

Your project sounds GREAT to me. I could measure one of my Husqvarna or Remington RB actions and give you the dimensions. I should point out though, that ALL of the pressure-containing parts of the AR platforms are 4140 "chromoly" or 446 "stainless". Some "whisper" rounds CAN (don't HAVE TO) generate 45,000 PSI. I don't know how an aluminum rolling block receiver would handle 'direct' pressure. And "don't know" is not a euphemism for "don't think". "I don't know" means I don't know.

That said, you could do it out of steel too. Just more difficult/takes more time.

Love to discuss it further.

Paul

[gitano]

From drinksgin

If I remember correctly, T 7075 has a tensile strength higher than cold rolled steel, an action of it might do nicely with 30,000 psi or less loads.
I still have thoughts about my own super simple ss action[in light of my super simple design skills],
May have to spend some time sketching.
Now, continue on Jeeves, ur, Gitano.
nra, tsra, goa, 2nd amm. jpfo, def con.

[gitano]

I got the lower parts kit this afternoon, and if I didn't need to 'fix' the buggered trigger hole, I would have a complete lower assembled. The trigger and hammer are ever-so-slightly wider than the cavity (0.681" for the parts, 0.671 for the receiver), which is "good". When I fix the trigger hole, I'll mill out the extra 0.010".

Speaking of the trigger hole, the trigger blade is too wide for the existing trigger hole. That too is "good". When I "fix" it, it will only be slightly larger than the trigger. Cosmetically, and psychologically, the "fix" will be a real fix, not just a 'cover-up'. I'm smiling again.

I am impressed with both the parts kit and the receiver. Both are well-made and surprisingly "standard". Like I said, I'm smiling again.

More pictures tomorrow.

Paul

PS - I have also been looking for magazines. Not too happy that there aren't any 5-rounders "in stock", and even more unhappy about the prices. However, I went into Sportsman's Warehouse to find some cheap .223 ammo to shoot and lo and behold they had some really cheap magazines. (No 5-rounders though. :frown ) I bought two boxes of the cheapest ammo ($8.99/20) and a $4.99 20-round plastic clip. It works great in the receiver. Don't know how long it will last, but I won't be as hard on it as some AR-15 shooters are, so maybe it will last longer than it's $4.99 price suggests. Regardless, it will be good - and cheap - for proofing the rifle. Still smiling.

Paul

[gitano]

From j0e_bl0ggs

slowly slowly catchee monkey...

[gitano]

From j0e_bl0ggs

Nice pic of the snow on THL when you went to collect the parts... BH would have a 'connery' (English humour)

[gitano]

The DPMS 'kit' is good. Had the receiver not needed 'fixing', I'd have an even bigger grin on my face. Was really happy to find the cheap magazines. Not great being plastic, but will last for a while 'til I work out the kinks.

The other barrel was also in the package. Nice barrel with gas block. It's a "rifle" length gas port location, but I don't really care for the .223 barrel. That barrel won't likely be shooting subsonic ammo.

Speaking of ammo, holy mackeral "hunting" .223 ammo is stupid expensive up here. $35 for 20 of Hornady, Remington, Winchester and whatever the others were. The absolute cheapest I saw for "hunting" ammo was $24/20 and that was some 35-grain stuff. I was happy to find the Federal 55-grain FMJ stuff for "only" $8.99/20.

Tomorrow, I'll finish the milling on the receiver, fixing the trigger hole and widening the cavity by 10 thou. Then I'll just have to sit around and wait for the upper to arrive. No notice of arrival from Midway today.

Paul

PS - Midway still says date of arrival of upper 2/24/12. So at least they haven't pushed it out later - yet...

Paul

[gitano]

From j0e_bl0ggs

Frikking A-Diddybags! as one is wont to say... (well not quite right)


You may want to take a few for your 'wild dog' hunting....

That 'dogtown' bullet is really quite superb.

[gitano]

From drinksgin

Looking good!
I was thinking, oh,oh, why are there a bunch of wildcats for sub sonic use?
.25-20, .32-20, .357 mag. and max. .30 carbine are available and I think would propel a heavy for caliber bullet at 1200fps.
Chambering and twist rates would seem to be the major holdups.
I worked up the 8x41R just to have something for the barrel Gitano sent me .
I still want a .32-20 just because it was the first cartridge I helped reload and cast the bullets for.
A .32-20 in usable shape is very high now.
I still remember seeing the barrels in the hardware stores and gun shops, $15 for .25 and .32 rfs, $25 for .25-20, .32-20, .25 rem. , .30 rem. ss, pump and self loaders, oh me.
I am thinking of getting a GM AK , .312" barrel, fitting it to a Handi action or making my own ssss, [super simple single shot], action and chambering it for .32-20, now just to get enough energy to start. :D
nra, tsra, goa, 2nd amm. jpfo, def con.

[gitano]

I am reminded of an old saw: "I've only been wrong once in my life, and that's when I thought I was wrong and I was really right."

First - It was impossible to measure the depth of the FCC without moving the workpiece completely out from under the quill. Furthermore, the distance between the top of the "Master Plate" and the top of the receiver was not uniform from one end to the other. In other words, the mounted Master Plate was not parallel to the top of the receiver. The measurements taken in the shop were taken with the workpiece mounted, and were confounded by the jig. (I shoulda known or at least suspected that.) The difference between the height of the master plate relative to the top of the receiver was 0.015" from left to right. Since I had leveled the workpiece/jig, I incorrectly assumed that the top of the jig was parallel to the top of the receiver. The short story is that the floor of the receiver was out of level by 0.015" and one end was "right on" at 1.250" and the other was too shallow by 0.008". It's level at 1.250" now.

Second - When I re-installed the lower parts after leveling the floor of the FCC, the "disconnect" problem did not go away. The only conclusion I could draw was that the parts weren't right. I was pretty steamed, actually. I fussed around for a bit trying to figure out how to determine for certain that the disconnect was actually mis-shapen. At the time I bought the AR-15 parts kit from Midway, I also bought a lower parts kit for the AR-10 receiver. It occurred to me - although I wasn't certain of it - that the "guts" of the AR-10 should be the same as those of the AR-15 because the FCC dimensions were the same. So I opened the AR-10 kit and visually compared the pieces. They looked the same. After measuring them in a few places, they measured the "same" - within tolerances. So I removed the AR-15 trigger/hammer group and replaced it with the AR-10 group. The new pieces worked properly. "OK", I say to myself. "That means the AR-15 trigger/hammer group is in fact wrong." Now I can confidently call Midway and discuss getting replacement pieces. I went on and installed the rest of the parts kit.

Third - I've been using a video I downloaded from the internet for the assembly instructions of the lower parts kit. The fellow doing the instruction had been doing a good job, and I had followed his instructions "to the letter". However, when I finished, I had an extra part. I hate it when that happens.[blink]  It was a little spring. I couldn't for the life of me figure out where this spring might go. However, it seemed at least possible that it might be associated with the disconnect malfunction. No word of a spring associated with the disconnect in the video, but there was an "exploded" view of the parts on the back of the cardboard advertising that came with the parts kit and an associated parts description list. I looked for the word "spring" and accounted for all of them I had installed EXCEPT THE DISCONNECT SPRING!  Grrr.... Looking closely at the disconnect, I could see where a spring might go, and looking at the rear of the slot in the trigger where the disconnect rested, there was a 'cutout' that the spring fit right in and the location of the cutout corresponded to the location of the cutout on the disconnect. I disassemble the trigger/hammer group AGAIN. I re-installed the AR-15 parts WITH THE SPRING, and voila', it worked like it was supposed to. Imaging that. First emotion was :D , then

As a footnote, I had to return to my shop an make a tool that would allow me to hold all the pieces in place at once as I installed the trigger/disconnect assembly.

Anyway, all's well that ends well I suppose. The good news is that I have a receiver that I completed, and while the finally-finished milling doesn't quite look like it was done with a CNC machine, I am quite pleased with the finish and the dimensions and wouldn't hesitate to show it to any machinist for fear of being ridiculed. Of course it took me a total of 7 hours to do.

I repeat that when one starts from 'zero', there's no place to go but 'up', and consequently I have learned a great deal through this exercise, and since I was working 'in the dark' for the most part, I'm OK with way things turned out. That's not to minimize quality of the jigs from TM. rather it's just a matter of being "alone" as I both machined the receiver and as I assembled the pieces of the parts kit. "Slowly, slowly, catchy monkey" as J0e_bl0ggs is wont to say.

I think I mentioned that I had "back-ordered" a complete upper from Midway. Their initial comments said it would be in to them on 2-26-12. They're pretty good about getting back-orders right out the door, so I expected it at my place about a week later, meaning this coming Saturday at the latest. Of course, on Tuesday they "amended" the arrival date to 3-24-12. :-s I'm not interested in waiting another month to get this thing put together. So, I called them up, cancelled the back-order, and ordered an upper that was in stock and ready to ship. I expect it in my hands either tomorrow or Saturday. Here's hoping. If I get it by Saturday, I COULD be shooting that same day. I emphasize "could", because I am beginning to realize that all is not as it is represented with these "kits". Again, that's not complaint. I am tickled to death to be able to complete fabrication and assemble an AR rifle. It is not at all unusual that "the devil is in the details" with a project like this. I still think it's 'the best thing since sliced bread".

Oh yeah. The trigger is really not good. Lot's of uneven creep and a final let-off that has to be at least 10lb. I suppose I will be replacing the DPMS kit trigger with a "real" one. I'll have a look as some videos of "trigger jobs" and see if I think it is worth it to work on it. I'm quite adept at removal and installation...

Thanks,
Paul

[gitano]

From DavidLT89

Geesh!!!!! i gotta check in more often. last time I was here you hadn't started anything yet!!!! Now your almost done!!!! very interesting I might ad!! I am curious as to how it performs!!! also, you mentioned you wanted some five round magazines but the "price" was disappointing, if you don't mind me asking, how much are 5 round magazines going for? Maybe I can get it cheaper for ya! keep up the good work. God bless.

[gitano]

Here's the cheapest 5-round plastic one and it's not in stock. http://www.midwayusa.com...n-5-round-polymer-black

Here's a steel 5-rounder not in stock.http://www.midwayusa.com/product/593609/ar-stoner-magazine-ar-15-223-remington-5-round-with-anti-tilt-follower-stainless-steel-black

Here's another steel one - not in stock. http://www.midwayusa.com...gton-5-round-steel-blue

Here's a steel "flush fit" - not in stock. http://www.midwayusa.com...nd-flush-fit-steel-blue

Here's a steel/plastic hybrid - IN STOCK. http://www.midwayusa.com...gton-5-round-steel-blue

Here's another steel one - out of stock. http://www.midwayusa.com...r-stainless-steel-black

Here's a plastic one that is probably a 30-round magazine with a block in it to make it hold no more than 5. http://www.midwayusa.com...mington-5-round-polymer

Her's a plastic one - out of stock. http://www.midwayusa.com...n-5-round-polymer-smoke

Here's a steel one for $45 and it's still out of stock. http://www.midwayusa.com...ton-5-round-steel-black

Notice a "trend"? None in stock. By all means check it out and if you can find me some 5-round magazines for $20 or less, let me know. Now compare the prices of the 5-rounders to the 10 to 30 rounders.Angry

As for "checking in", you can go to the top of the page, click on the "Options" link, select "watch", and you will be notified of any new posts.

Paul

[gitano]

From Jorge in Oz

David wrote:
Geesh!!!!! i gotta check in more often. last time I was here you hadn't started anything yet!!!! Now your almost done!!!! very interesting I might ad!! I am curious as to how it performs!!! also, you mentioned you wanted some five round magazines but the "price" was disappointing, if you don't mind me asking, how much are 5 round magazines going for? Maybe I can get it cheaper for ya! keep up the good work. God bless.

I'll second that David. Last time I check there were photos of the parts purchased. SoonPaul will be shooting his AR. Fascinating stuff Paul keep up the good work. As 22 Hornet said we can't mess with stuff like that Down Under so its most fascinating.

Cheers

Jorge

P.S. on watch now. Thanks Paul.
“The Germans brought the best hunting rifle to the war. The Americans brought the best target rifle. The British brought the best battle rifle!”



"Law and order break down as a direct result of placing political correctness above equity and truth" Mark Jenkins

[gitano]

From DavidLT89

I did not know about the "watch" option, I have tagged it!!! as for the magazines, the wholesaler has bushmaster mags, I am assuming they are steel, for around 25.00. BUT, there is nary one in stock there also. I will keep my eyes open, it may come down to who can actually get one in stock!!!!! God Bless.

[gitano]

To our friends in Canada, Great Britain, and Australia; you have my sincerest sympathies. I know at least some of you that would love to be allowed to do something like this. You can imagine how significant I feel this is, given that it took something like this, (finish your own receiver), to get me to consider 'playing' with a semi-auto rifle. Especially one that is essentially a clone of a military firearm.

That said, from a cost perspective, "building" one's own firearm instead of purchasing it over-the-counter (OTC)is very conceptually similar to reloading relative to buying OTC "factory" ammunition. Specifically, reloaders rarely actually reduce the total amount of money they spend on their "hobby", BUT - and it is a BIG BUT - they 1) get what they WANT, not what some manufacturer thinks they should have, 2) make more of it for the same price, and 3) 'personalize' it. (Just to name some of the BIG "pros" of reloading.) BUT... reducing the total amount of money spent is not 'reality'. I could have purchased a "stock" AR-15 in .223 Rem/5.56 NATO for $650 and been shooting three weeks ago. While I haven't yet 'tallied the score' on this project, I can assure you that I very quickly exceeded that $650 figure.

The 80% receiver kit was $425 alone and the upper was $400. (It should be kept in mind that the majority of the cost of the receiver kit - about $275 - was for the jigs, AND I got TWO receivers - one AR-15, and one AR-10). So that $825 isn't exactly "apples to apples" with the $650 OTC purchase of a ready-to-shoot firearm. Plus there have already been "Butt kits" "receiver parts kits", another NEW barrel, and I haven't even started getting the pieces for the custom piece for the custom upper. Most important for me to keep in mind as I consider the costs, is what my ORIGINAL goal was - a legally suppressed firearm in a cartridge of MY choosing. Right now, THOSE kinds of AR-type firearms - a legally suppressed firearm in a custom chambering - cost anywhere from $3000 to $5000 "over-the-counter".

Also, what was actually the utmost importance to me was the act of making (in truth "finishing") my own receiver. THAT really makes this firearm MINE. I LIKE THAT. I must be honest and say that I look(ed) forward more to the "work" involved in this project that I do shooting it. AND... anticipation of making the unique 8mm barrel, cartridge, and suppressor, greatly exceeds the anticipation of shooting it. That's not to say I don't look forward to shooting it and expect it to put a big grin on my face, but the "building" of it is really what keeps the fire burning.

Today is about like Christmas Eve: The upper MIGHT be here at the post office today. If so, there is a very real possibility I will be 'proofing' the build this evening. :D

Paul

[gitano]

No "Christmas" today. :cry:

Maybe tomorrow.

Paul

[gitano]

From 22hornet

Great progress Paul. How many hours of work have you invested in this project to date?
I take it with the machining jigs and all it's a project the average bloke could take on?

And what is the "watch" function?

[gitano]

22hornet - Mill time has been about 10 hours I'd say, and that's because I'm slow and inexperienced on the mill. "Fiddling" time - installing the lower parts kit and other sundry 'stuff' probably pushing another 10, but that's because I'm inexperienced.

The real value of the jigs is getting the trigger, hammer, and shot selector holes EXACTLY right. I will not use the templates for milling the "Fire Control Cavity" again. They really just get in the way, make it necessary to use "long" mill cutters, and make it difficult to see the work. They have marginal value for "layout", but with good blueprints, they really aren't necessary. I won't use them when I mill out the FCC for the AR-10.

This IS a project an "average bloke" could take on as long as that average bloke could walk and chew gum at the same time. Patience and attention to detail are really all that are required. There are many folks apparently completing these 80% receivers using a drill press instead of a mill. I suppose I would be willing to try that if I didn't have a mill, but I would not even THINK about it if I could get access to a mill.

If you go to the top of this page, you will see the word "Options" to the far right of the title of the thread ("AR Build - First"). If you click on that "Options" you will be given four options. The first one should be "Watch" or "Watch this thread". If you select that option, you will be notified of all new posts to this thread.

No joy today at the PO either. Now I'll have to wait 'til Monday.

Paul

[gitano]

From j0e_bl0ggs

And how did you get on cutting the 16tpi full form thread for the 8mm barrel?

[gitano]

Haven't done it yet. Got 'otherwise occupied' yesterday. Had to go to Los Anchorage. Ate up the whole day.

Paul

[gitano]

Hokay...

Don't forget that the original idea here was to build an 8mm Kurz-chambered, suppressed rifle.

One of the initial uncertainties I had - and a potential 'deal killer - was the breech. I couldn't tell from looking at pictures whether the breech of an AR rifle was part of the upper receiver and the barrel screwed into that breech - like on a bolt gun - or if the breech of the gun was actually machined into the barrel. If it was the former, I was "OK". If it was the latter, I wasn't "OK" because the bolt of the AR-15 has 8 locking lugs that "lock" into the breech and while I MIGHT have the tools to do that, I was just about certain I didn't have the skills to do it well/right.

Turned out, that the breech is actually part of the barrel. :cry: HOWEVER, the REALLY good news was that the breech was actually a separate piece of metal that one could buy and screw onto the barrel. The particular piece is called the "barrel extension". (It SHOULD be called the breech.) Here's the one I bought from Midway: http://www.midwayusa.com/product/169485/dpms-barrel-extension-ar-15-stainless-steel

However, once I get 'fired up' on a project, I like to get after it, and so I decided to pick out an 8mm barrel, cut it to length, and thread the stub for the extension. This right after I ordered the extension. So I did. When I got the extension, it didn't fit on the barrel stub. Not a big deal since the stub was too large instead of too small. I just had to put it back in the lathe, re-time the thread set-up, and cut the threads "a little" deeper. I had cut them to the mil-spec, but since the extension didn't go on, they needed to be smaller. I took care of that today. While I was waiting for other "stuff" to happen, I ordered some "Full Form" thread cutting bits for my lathe. They make cutting threads much easier. (I got them off of eBay from some guy in Germany, and they were in my hands in less than a week. :D)


Here is what the stub looks like when I finally got it to proper size for the extension:


After I took 0.025" off the extension fit VERY tight, so I took another 0.002" off and it is a nice 'snug' fit. I can get it on by hand, but I have to use some muscle.

The thread-cutting tip is to the right. It has chips and lube on it, but you can see one of the other points.

Here is the extension screwed on:


And here is the extension on the stub showing the hole through which the extension is pinned to the barrel:

Here is the "business end" of the extension - the breech:

I ordered some pins to pin the barrel extension to the barrel, and should have them by Thursday. I'll pin the extension on the barrel then.

I was also planning to thread the muzzle for the suppressor today, but I can't find my 1/2"-28 Full-Form threading inserts. I could use my regular 60-degree inserts, but it's SO much nicer to use thread-cutting inserts, and since I want to get the .223 version completely built and shooting flawlessly before I tackle the gas system for a suppressed 8mm Kurz, I've got plenty of time to get the muzzle threaded for the suppressor.

God willin' and the creek don't rise, I'll have the .223 upper tomorrow. I'll be performing a function test soon - very soon - thereafter.

Paul

[gitano]

From j0e_bloggs

Looking good....:D

[gitano]

IT'S ALIVE!!!

Received the upper this afternoon. Took about 5 minutes to inspect it, install it and test fire it. I and the rifle still have all our parts intact and in good working order.

:D:D:D:D:D

Difficult to express what a treat it is to hold this ugly baby.

Here are some "baby" pictures:



The upper fits VERY snug to the lower.





Barrel and handguard are 'fine'.





Now I have to get down to business getting the 8mm barrel, and all the associated pieces, installed.

YeeHAAAAA!

Paul

PS - Just for record keeping sake, I ordered the 80% kit on 1/31/12. I got the kit on 2/23/12. I test fired the gun on 3/5/12. That ain't too shabby, AND I had to wait two weeks for Tactical Macnining to get the kit in stock. In reality, 11 days from receipt of 80% receiver to full-function rifle. :D

Paul

[gitano]

From j0e_bl0ggs

Chuffed....:D

[gitano]

From j0e_bl0ggs

Colleague (Jim) here concurs with..... ohhhhhh yeahhhhhh!

[gitano]

From DavidLT89

I don't think there is anything ugly about it!!! quite the contrary, that is one sharp looking gun!!! Congratulations on a job well done my friend!!! I "cleaned" one of those more times than I like to remember!!! God Bless.

[gitano]

Thanks! David.

I'll bet you did. Even though my military days harken back to Viet Nam, I don't think I ever even shot one of these before yesterday. If I did, it wasn't memorable. I certainly didn't in the Navy.

I think the "hard part" lies ahead - getting the 8mm version 'up and running'. Gotta get gas block, gas tube, new bolt, and other barrel paraphernalia. Once the parts are assembled, I'm anticipating A LOT of 'fiddling' to actually get it to WORK in subsonic configuration. Actually, as I look ahead to what there is YET to do, I doubt if I am even half way 'there' yet. But...

I'm hoping it turns out as rewarding as this has been.

Paul

[gitano]

So I wanted to get the AR-10 receiver milled so that I could get it ready for an upper. Since I already had the trigger, hammer and shot selector holes drilled, I was not going to use the jigs except for setup. I would then mill from the datum point. I was planning to use this drawing to set everything up,

but when I got ready to do it, I realized that these dimensions were for the AR-15, so I had to recalculate everything.

The first operation I was going to perform was drilling the 7 mid-line holes, so I had to make sure that the long axis of the receiver was parallel to the x-axis movement of the mill's table.

Here's the setup with the dial indicator at one end of the work-piece.


Here it is at the other end:


I didn't figure you could see the dial very easily so here are pictures of the dial at each end.




The alignment was different by less than 0.0015" over 3+ inches, so the max misalignment per inch was something less than 0.0015/3 = 0.0005"/in. I could live with that.

You'll note in the pictures that the mid-line and and the centers of the holes are already marked. That's because I did all of that before I remembered to take pictures.

Here's what the setup looked like:




Here is making sure that the drill is in fact drilling on the center-line.



And as the first hole progresses:






And the second hole:




And the third hole:




And starting the 1/2" holes:




















And they're finished:










Then I setup the outline of the "Fire Control Cavity" (FCC):








You'll notice the one ratty side. That was a crappy NEW Chinese side mill I just got. I took it off and used my short, but good, end mill.

After that was laid out, I had to make sure the receiver was level relative to the movement of the x-axis.

One end:


The other end:


Within 0.0005" over 3.655".

Once leveled, I commenced cutting:









And finished up about 5 hours after I started:


You can see a "rough" spot in the rear part of the cavity. The end mill "caught" something, I'm guessing a chip, and 'dug in" to the bottom. Looks worse in the pictures than it is.

I am very pleased with this machining job. You can't tell from the pictures, but it is much better than the first pass on the AR15. I'm quite pleased with this one. It's much easier to do without the top plate of the jig. The top plate is still good for layout, but it's just in the way for the actual cutting.

I'll put some pictures together of assembling the "innards".

Paul

[gitano]

From j0e_bl0ggs

Looking good, well done!

Think you need a de-burring tool Noga make good ones...

[gitano]

Thanks, j0e_bl0ggs.

I'm going to "custom fit" the trigger hole to the trigger and then this 'thing' should be 'done' with respect to the lower parts kit. Have to get a butt-stock kit, then start working on acquiring the upper parts.

At the moment, the only two chamberings being considered are the .308 Win/7.62 NATO and the 808 (8mm bullet on .308 Win case). As strange as it may sound, I'm leaning toward the "standard" .308 version. In the end, this rifle isn't going to be suppressed, or if so, it will still be supersonic. That being the case, "easy" is most readily accomplished with the "standard" case. I'll probably 'save' the 808 for a special bolt rifle.

More when there is more.

Paul

[gitano]

From Jorge in OZ

Hi Paul,

The finished product looks great. Sorry I haven't replied earlier as my wive will be having our little girl any minute now and here I am sitting at work when i should be at home and I'm posting on the forum. Great machine work. Hey the more you do of a thing the better you get at it. I believe it's beyond my capabilities but if you don't have a go you'll never know. It's great how you have taken pictures step by step it makes us feel like we are part it. Thanks for taking the time out to do that. It's been interesting reading. Have a great day. If you don't hear from me it will be because our little girl has arrived.

Cheers

Jorge
“The Germans brought the best hunting rifle to the war. The Americans brought the best target rifle. The British brought the best battle rifle!”



"Law and order break down as a direct result of placing political correctness above equity and truth" Mark Jenkins

[gitano]

HOORAY on the new arrival!

Here's hoping all goes smoothly for mother and child. Keep us posted on how things go and the "vital statistics".

Thanks for the comments. It is quite true that the more you do it the better you get.

Paul

[gitano]

From drinksgin

Never shot an M-16 but TDCJ has AR 15s in the guard towers and everyone who worked inside a unit had an annual qualification with the .357 revolver, 870 shotgun and AR 15, my opinion was that it was a plastic thingy with a recoil absorbing butt that had no recoil anyway.
Felt funny, more like a Buck Rogers secret ray gun.
I am just old fashioned, like wood, just about any kind and something that has enough recoil you do not have to check to see if it went off.
Never the less, this thing should be fun with the 8mm whisper, need to have a proof run on some thin skinned animal , soon.

[gitano]

First I've got to get the 8mm built.

I've been working on making a wrench for torquing the barrel extension on the barrel. First version was on wrong steel - 12L15 - which has a lot of lead in it and is too soft. Second was too short for the dividing head/quill proximity, (the mill's quill hits the dividing head jaws), so I have to "fix" that.

The extension is supposed to be torqued to 130-150 ft-lbs. I don't think it needs to to be NEARLY that tight, but I'll do 130 just because I am inexperienced. I think the reason for the high torque values may be the heat/cool cycle created by battlefield semi and auto firing. Of course it could just be typical "gunsmith" stupidity too.

I'm waiting on new low-profile gas block so I can put free-floating handguard on .223 version. The barrel nut (not the barrel extension) is supposed to be torqued on between 30 and 40 ft-lbs. I'm sure the 'factory' torqued this barrel nut on to AT LEAST 150 ft-lbs. I had to use a hammer on the wrench to break the nut loose. This is the second rifle I have owned where the barrels are MADE to be switched, and the second rifle in which the "factory" torqued the nut on so tight that the wrench had to be beaten with a hammer to loosen the nut. Gee, I wonder why they would do that? (Don't bother answering, it's a rhetorical question.)

I'm working on acquiring all of the parts for the A-10 upper. This will probably take a while. First because they are "out of stock" except in versions that have STUPID prices, and second, even the "cheap" ones (that are out of stock) are WAY over-priced. That should be easy to understand for those that have an appreciation of the stupidity of the pricing of Ruger 10/22 parts now that the rifle is so popular. The AR-10 is in the same category, but WAY, WAY more insultingly OVER-priced relative to the cost of manufacture. Here's a PERFECT example: The parts kit for the lower on the AR-10 is identical - AND I MEAN IDENTICAL - to the parts kit for the AR-15. The lower parts kit for the Ar-10 is $10 MORE than the IDENTICAL parts kit for the AR-15. THAT is what I mean by "stupidly" priced and "insultingly" priced.

So I am 'wandering' the internet looking for "deals" on parts for the AR-10 upper. These "deals" will be prices that are only "silly-priced", not stupidly priced.

One conclusion I have come to is that since subsonic muzzle velocity is, by definition, below the speed of sound, there is no particular reason I can see for using the AR-10 in subsonic mode. All of the cases that are suitable for the AR-15 platform are suitable for subsonic application. On the contrary, the .308-sized cases do not have particularly good internal ballistics when put to subsonic use. So I am working on selecting the right cartridge for the subsonic use of the AR-15.

The 8mm, while a favorite caliber of mine for supersonic use, is not so great for subsonic use when compared with other larger calibers. The only thing keeping me hanging on to the 8mm is the fact that I have a mess of 8mm take-off barrels. The .375 and .416 calibers show excellent subsonic internal and terminal ballistics with the Flying Beer Keg (FBK). So for subsonic application, the FBK WILL come into reality even if I have to make them one-by-one.

I'll post pictures of the wrench fabrication when I get it finished.

Paul

[gitano]

From drinksgin

GM has a .308, chambered, 22"x 1.25" barrel, $35 and 10mm, .44, .45 and .475 barrels for about $40.
You might do something with one of those.
A .45 or .475 at 1200fps or less would make a loud whop when it hit.
nra, tsra, goa, 2nd amm. jpfo, def con.

[gitano]

I've been looking at Green Mountain barrels and WILL be getting some of them. I ordered a .338 for Grant - the fellow with the cabin in Skwentna. At the moment, I'm crunching the internal and terminal ballistics for .323, .338, .358, .375, and .416. I think getting anything above .430 to work in the AR-10 will be a challenge. Certainly 'doable', but probably not worth the hassle. There ARE cartridges in .458 (.458 SOCOM) made for the AR-15 platform, but I don't think I want to try to get brass. Up to .430, I can use necked up 7.62x39 brass with a 7.62 bolt, or I can go up to the .308 case necked up and shortened to 45mm. I'm leaning toward the latter.

The big costs are the action parts. The bolt carrier group for the AR-10 is difficult to get for less than $250, and THAT is a STUPID price when you get one in your hands and see how crudely they are fabricated. A STRIPPED AR-10 upper is AT LEAST $160. THAT is positively insulting. An "assembled" upper is over $250, AND THAT DOESN'T INCLUDE A BOLT CARRIER GROUP! Please tell me how "assembled" doesn't include a BOLT! That's like buying an "assembled" car that doesn't have an engine! The whole AR-10 "community" is very frustrating - both the scumbags that sell at absolutely ridiculous prices, and the idiots that buy at those prices. A perfect example of what can go wrong with a free-market.

What has become patently obvious, is that it doesn't matter what bullet one uses at subsonic muzzle velocities, the trajectory over 100 yd is the same whether it is a .22 or a .510. With the 'scope mounted 1.97" above bore, and a 4" target size (2" above and below line-of-sight), the sight-in range will be 85, plus or minus 1 yd, and the drop at 100 will be 2.1". Again, regardless of weight or caliber. THAT means that the only aspects that matter are internal and terminal ballistics.

The internal ballistic issues are:
1) Load density - I want it between 50 and 105%
2) Burns 100% in the barrel, the sooner the better, because that keeps powder out of the gas tube and suppressor.
3)High enough pressures - above 25,000 PSI - to make for good gas seal and positive action operation. Although the positive action operation is not too big of a deal.

Terminally, it's simple:
1) Deliver as much energy to the target at 100 yd as possible while keeping muzzle energy (recoil) "friendly".

I'm going to post some results from paper-whipping this. They were interesting to me in what came out as unimportant.

Paul

[gitano]

From drinksgin

The AR platform does not sound as though it is very friendly and the vendors sound worse!

[gitano]

Then I didn't express myself well. The "AR" platform is AMAZINGLY versatile. AMAZING! And just about anyone can 'mix and match' with ease. The problem is the "community". Idiots that buy into any macho, "y-chromosome" BS, and a bunch of "wannabes" that care only about how much money they CAN make.

The AR-10 platform - the "big caliber" version of the AR-15 - has considerably less "utility" in my mind than the AR-15 does. HOWEVER, if you want to shoot .308 Win/7.62 NATO and larger cartridges from an AR platform, the AR-10 is the way to go. You CAN shoot "bigger around" from the AR-15 platform, but you can't shoot it "big". Bigger than .223 caliber is best used in "special" - like subsonic - applications.

Paul

[gitano]

From drinksgin

I have seen AR 15s here for about $500-600 in .223, just never felt a need for one.
nra, tsra, goa, 2nd amm. jpfo, def con.

[gitano]

The cheapest you can get an AR-15 here is $650, and the next step in price starts at just over $900. If you handle them and compare manufacturing and quality to ANY newly manufactured bolt gun, they should cost about $300.

Paul

[gitano]

http://www.midwayusa.com...ped-lr-308-forged-matte

Using the "80%" receiver, I can get/do this for $125. For the AR-15 - $80.

Just stupid.

Look at this for a "matched" set of upper and lower: http://www.midwayusa.com...for-dpms-magazine-matte

Note that these are "stripped".

Paul

[gitano]

From drinksgin

Dealing with those people is not nice.
I think it is a case of gouge until the purse runs dry.
URP!
Certainly inspires customer loyalty.
nra, tsra, goa, 2nd amm. jpfo, def con.

[gitano]

I don't blame Midway for these prices. They have too many other good prices on things not AR. I am convinced, based on looking elsewhere, that it is the manufacturers that are doing the gouging. This is the worst price-gouging I've seen in the US.

Paul

[gitano]

From drinksgin

I did not mean Midway, they just pass things on with enough markup to make a reasonable profit, which they must do to stay in business.
No, it is the manufacturers who are the villians in this instance.Angry
nra, tsra, goa, 2nd amm. jpfo, def con.

[gitano]

From 22hornet

I've looked on you tube and found some videos on guys completeing the same project.

How are you going to finish the rifle Paul? Anondize the aluminium or some sort of spray on coating like Cerokote?
Are you planning on doing this yourself?

[gitano]

I'm still wrestling about the finish. At the moment there are two prime candidates: CeroKote and leaving it 'natural'. The CeroKote is apparently a great finish, but it's a bit of a challenge to get geared up to do. I'll probably go that route. I ordered some color samples from them and wasn't impressed with the colors. The finish is fine, but the colors were dull.

I've been 'pressing on' with this and the AR-10 build. I have the butt and upper for the AR-10, and the bolt carrier and bolt 'kit' but no bolt. Been doing A LOT of number crunching to try to figure out what subsonic cartridge to go with. The jury's still out on that on. I THINK I'm going with the 33mm case and the 8mm bullet.

For the AR-10 I think I'm going with the .308 Win AND a .375 bullet on a .308 case. That case and the 260 Accubond are a good match for that platform.

Pictures soon.

Paul

[gitano]

From 22hornet

If you want a shiney Cerakote finish "Midnight Blue" comes up pretty good. I like the more matt finishes though. "Sniper Grey" or "Graphite Black" look good to me.

[gitano]

Actually, "Midnight Blue" was one of the color samples I got, and it is indeed quite shiny.

While I didn't order the "Graphite Black" sample, it is one of the "black" colors at the top of the list. The "Burnt Bronze" looked good on the website, but not 'in person'. It was considerably more drab - and by that I don't mean "matt" - in reality than the web pictures.

I did purchase a small hand-held sand blaster in order to provide the 'rough' texture required for the CeraKote process.

At the moment, I'm concentrating on getting the 8mm subsonic cartridge chosen and the barrel fabricated and installed. There is really A LOT to that decision and fabrication. For instance: Using the .223 case has several advantages. However, if I use the .223 case, I have to cut the entire chamber off of the existing take-off barrels - that I have in hand - in order to get to a place on the barrel I can cut a .223-sized chamber. The 7.62x39 case has essentially the same problem. Using the Kurz case (7.92x33), that has a "standard" .470" rim and head, means I can salvage some of the existing 8x57 chamber which in turn means that I have enough of the chamber OUTSIDE diameter remaining to provide the shoulder necessary for the barrel extension to butt up against. However, the Kurz case MAY be problematic with respect to feeding from the "standard" magazine, AND it requires a ".308 Win" bolt face which is much harder to come by in the AR-15 platform. If I go with a .308 Win case shortened to 45mm I can shoot 150-grain bullets at very nice hunting velocities - 1000+ ft-lb of energy at 300 with impact velocity of 1800+ f/s - and have 'good' chambering, but... I'd have to fabricate cases and use the .308 Win bolt. And those issues are just the tip of the cartridge decision iceberg.

I'm accumulating the ancillary parts - gas tubes and blocks, barrel extensions, index pins, hand-guards, barrel nuts, etc. - while I contemplate the cartridge choices. Cartridge choice is a BIG commitment as it impacts every aspect of the long-term future with this rifle. I think I'll have a decision on the cartridge within a few days.

Paul

[gitano]

From 22hornet

I thought that .308" size bolt size was common in AR's in the USA? Is the problem getting them or the $$$ they are charging?
Are you able to make up some dummy 8mm Kurz cartridges and send them to someone who has an AR to check for any feed problems?

You mentioned using the .223 case. Is an 8mm/.223 one of the options you are looking at? Wouldn't that be too long to fit into a standard .223 magazine?
I would have thought the .308x45mm with a 150gn projectile would be too long as well?

[gitano]

22hornet wrote:
I thought that .308" size bolt size was common in AR's in the USA?
They are "common" for the AR-10, NOT the AR-15... EXCEPT that the 450 Bushmaster (made specifically for the AR-15) is made on the .284 Win case. It therefore has a .473" rim, meaning that it has a "standard" .308 Win bolt. This is just one among MANY silly "things" about the AR platforms.

Is the problem getting them or the $$$ they are charging? Yes. :)

Are you able to make up some dummy 8mm Kurz cartridges and send them to someone who has an AR to check for any feed problems?
Already done it myself with my own magazines. No apparent problems, BUT... That's only with respect to magazine fit and load. I've got to get the barrel mounted to test actual feeding. When looking at the loaded mag and the barrel extension mounted on the 8mm barrrel, it LOOKS ok. We'll see.

You mentioned using the .223 case. Is an 8mm/.223 one of the options you are looking at?
Very seriously.

Wouldn't that be too long to fit into a standard .223 magazine?
Nope. Keep in mind, one can always adjust the seating depth (up to a point) to accommodate cartridge overall length constraints.

I would have thought the .308x45mm with a 150gn projectile would be too long as well?
Again, seating depth can be adjusted as needed. However, also note that the OAL constraint on the AR-15 (magazine dimension) is 2.26". 45mm (also the .223 case length), is 1.772". That's plenty for both the 8x.223 with any 8mm bullet including a 3-caliber-long Flying Beer Keg.
The shortened to 45mm .308 case is getting "big", but it's not as big as the 450 Bushmaster cartridge, so I am encouraged.[/QUOTE]


Paul

[gitano]

Maybe some pictures of some of the cartridges being considered will be helpful...



Starting from the left:

1) 8x57 with "Flying Beer Keg" (FBK) simulator (pretty close actually). This is loaded to the COAL of the AR-10 (2.800"). It fits the magazine.

2) 8mm-08 - .308 Win case necked up to 8mm. FBK loaded to AR-10 COAL.

3) "8x45" which is .308 Win case shortened to 45mm. Loaded to .223 Rem AR-15 COAL of 2.26". Fits magazine.

4) .357 Maximum. Loaded to AR-15 COAL.

5) 8x57 Maximum. Loaded with 220 Sierra BTSP. Longer than Ar-15 COAL.

Maximums are not really 'in the mix' as the case is rimmed. I don't particularly have to deal with that issue since lots of other non-rimmed cases are available.

6) .358x39 - 7.62x39 necked up to .358 and loaded to AR-15 COAL. Fits and cycles in AR-15.

7) .338x39 - 7.62x39 necked up to .338 and loaded to AR-15 COAL. Fits and cycles in AR-15.

8) 8x39 - 7.62x39 necked up to .323 and loaded to AR-15 COAL. Fits and cycles AR-15.

9) Actual 7.62x39 - Fits and cycles AR-15. Not a candidate, but in for comparison.


There are two more x39 cartridges being considered - the .375x39 and the .416x39. I just haven't made dummy cartridges up for them.

10) 8x223 Rem - .223 Rem necked up to 8mm and loaded with FBK to AR-15 COAL. Fits and cylcles.

11) .338x223 - .223 Rem necked up to .338 and loaded to AR-15 COAL. Fits and cylcles.

12) 8x223 Rem - .223 Rem necked up to 8mm and loaded with 150 Spitzer to  AR-15 COAL. Fits and cylcles.

I thought .338 was the biggest one could blow a .223 case out to, however, recently I have read about someone blowing a .223 out to .358. I have inquired about how it's done, but have not received an answer.

13) 7.92x33 Kurz - Loaded with 180 cast spitzer. Loads and cycles in AR-15.

14) 7.92x33 Kurz case. There are four more cartridges based on the Kurz case 'in the mix' - .338, .358, .375, and .416. No dummies made up for them yet. However, with FBKs loaded to .67 calibers deep, they are shorter than the AR-15 max COAL of 2.26".


Below are some graphs that consolidate the data in a spreadsheet I developed to estimate the volume of the suppressor needed for each cartridge in consideration for this project. If any of you have MS Excel and want the spreadsheet let me know.

There is a graph for each CALIBER being considered. Within each graph, data for each separate CASE is presented for barrel lengths from 16" to 29" for the 8mm and 16" to 26" for all other calibers. The 8mm gets analyzed on out to 29 inches because I have 29" 8mm take-off barrels on hand.

The first set of graphs is the required volume for a suppressor for a specific case, with a FBK loaded, versus barrel length. As you can see, as the barrel length increases the volume of the suppressor decreases. For the subsonic application, the MV is constrained to 1050 f/s. For the cases shorter than 51mm (.308 Win), the COAL is 2.26". For the 51mm case, the COAL is 2.800". The lower the value, the smaller the suppressor. The vertical scale on each graph is the same so the data can be visually compared. For comparison, it is the relative values that are important. The actual values are only important in design of the actual suppressor after a cartridge is chosen.



The next set of graphs are the same, except in supersonic application. Here, the bullet is NOT a FBK but rather the one that gives the most delivered energy to 300yd.



The next sets of graphs compare the cartridges in the context of the ratio of the delivered energy - to 100yd for subsonic application, and 300yd for supersonic application - to the required volume of the suppressor. Since in the subsonic application, the muzzle velocity is constrained to 1050, all the cartridges within a caliber have the same terminal energy. However, for the supersonic application, the delivered energy is dependent on the MV AND the bullet used. The higher the values, the more energy delivered per cubic inch of volume of the suppressor.

First subsonic:


Then supersonic:


These look small to me. If you want to enlarge them on your screen, hold the "Ctrl" button down and tap the "+" key until they are as large as you want.

Paul

[gitano]

From 22hornet

Good work Paul. As they say a picture is worth a thousand words.
And looking at the ballistics you have posted these cartridges should work for you, provided you say within reason. Which I know you will.

And just to throw it in the mix too the little .280/30 British should work well on an AR platform provided you use suitable projectiles such as Speers 115gn HP.

[gitano]

Actually, 22hornet, I think you could use any bullet you wanted in that case on the AR platform. The specs I see state that a max chamber pressure of 50,000 is "fine" for the AR-15. That should launch just about any .30 cal bullet at reasonable MVs from that case.

It's a 'spiffy' firearm platform. I am genuinely disappointed that it has been commercially hi-jacked by "Madison Avenue" - AKA the advertising industry - to the point that prices are truly absurd with respect to the quality of the item vs. the retail cost. I know of no other product in the US in which the gouging is so blatant AND so extraordinary.

Pau

[gitano]

When I first started this project Midway had a replacement barrel on sale. It was an 18", "bull" profile, 1:7 (fast) twist rate (TR), and most important, the cheapest on the site. I was most interested in the 1:7 TR as I wanted to shoot some of the really heavy .224 bullets, and maybe subsonically. I would certainly need that TR if I had any hope of gyroscopically stabilizing an 80-grain .22 bullet, and I would probably need it even for supersonic use.

Rockinbbar impressed upon me the absolute requirement for a 'floating' handguard if I wanted the best precision I could squeeze from the rifle, so I bought the least expensive one Midway had: a Hogue aluminum "carbine-length" one. $50! And that was the CHEAPEST ONE!

The 1:7, bull barrel came with a gas block, but not a gas tube, and it had its gas port at "rifle" length, (as opposed to "carbine" or "pistol"), so I needed a "rifle" length gas tube as well. Cheapest one - $13.

I'm getting ready to get out and do some predator calling, and the AR-15 is coming along, so I was installing and sighting in the new 'scope AND installing the new barrel today. I did everything, (not the sighting in), while sitting in a chair in the den. This platform is amazing. Anyway, here are some pictures of the piece as it sits ready to hunt. (You can compare them to the pics in post #36 if you want to see the changes.)







It shoots straight with 'cheap' federal "military" (5.56x45 NATO) ammo. I just got it "on" at 100 so I don't have any targets to show, neither did I run it over a chronograph. I'll do all of that when I start handloading for it. For predators, cheap, FMJ 55 grainers out of "military" brass shooting about 1MOA will be fine for the time being.

Paul

[gitano]

From j0e_bl0ggs

Coming along nicely....

what cartridge will you decide on???  (8mm)

[gitano]

Still wrestling with that...

Short list is .223, 33mm Kurz, and x39mm.

Paul

[gitano]

From 22hornet

Now it's all coming together Paul. Looking like a real rifle now.

[gitano]

Thanks, 22hornet.

I forgot to mention that I replaced the original "factory" trigger springs with a "4 lb" set.

Makes a difference.

Paul

[gitano]

Since I had to psychologically cross the "ugly bridge" to even consider this project, I have felt a certain emotional liberation with respect to what I can hang on this thing and not feel like I am making it any uglier.

The 'scope you see in the above pictures is a brand spanking new Simmons 6-18x40 that I recently got off eBay for $40. I LIKE the new Simmons 'scopes with the side focus. A LOT. I was a little bummed by having to put that scope on the AR-15, but it was 'OK' because I was getting the gun in 'fighting form' in prep to take it 'varminting'. However, when I was down in the sanctum sanctorum, I happened to notice that one of my Ruger No.1s had another Simmons 'scope on it that I really didn't like on that gun. I had put it on that rifle just so I could work up specific handloads. (The No.1 is chambered in .308 Win.) I also got that scope 'for a song', but I don't 'like' it because it has a 50mm objective. Also, if a scope is going to have a 50mm objective, to my eye, it needs to be longer than this 'scope is. I don't particularly care for Hunting gun 'scopes with objectives larger than 44mm, and 40 is 'better', aesthetically, to my eye. I bought this one because it was cheap, and I intended its use only for load development. It is a 3.5-10x50 with a stadia crosshair and some kind of 'bullet drop compensator'.

As I looked at it, I realized that it would be 'perfect' for the AR-15. 'Looks" don't matter, and the 50mm objective would help with light gathering after dark on moon-lit snow. (No artificial lights allowed in AK for hunting ANYTHING.) Conversely, the 6-18x40 would be 'perfect' for the No.1. :D

Here's what they look like now.





Paul

[gitano]

From drinksgin

More Buck Rogers by the minute! :D
nra, tsra, goa, 2nd amm. jpfo, def con.

[gitano]

I used that exact term to describe to Susan what the appeal of the AR was to the 'younger generation'.

Paul

[gitano]

From Alboy

I agree on the scope swap and am glad the thing shoots for you guys.

In my case I entered the service shortly after these things and had to shoot the early models which I fear ruined me forever on the gun. To fragile and persnickety for my tastes. Jams on the firng line were common and the guns were clean.

My boy has a couple of new ones and they shoot fine but it just does not twist my crank.

[gitano]

Hey, Al.

Well, I woulda said pretty much the same thing a while ago, but I got hooked on the subsonic idea, and once you get past 'ugly' they are an amazingly versatile and mutable platform that just about anybody can modify themselves as long as you have the money to buy the over-the-counter parts.

I'm still enamored with the ability to swap barrels pretty much at will. I honestly would consider a barrel swap 'at the range'. They are also very 'tunable'. While the thought of Hunting anything but varmints with one is still not in my vision, I wouldn't be embarrassed to be seen killing varmints with one.

I think most of the common malfunctions of the early days have been resolved. You gotta tune 'em, but when tuned, they function as expected. I have NO IDEA how they perform these days as a battlefield weapon.

Paul

[gitano]

From j0e_bl0ggs

Yeah yeah ar etc. etc......

Going to have to teach you about good optics...

[gitano]

You have your work cut out for you.

By the way, I was reading where an AR-15 that shoots .22 RF is legal for "regular Nigels" in the UK...

From Wikipedia:
United Kingdom
As with all semi-automatic, centerfire rifles, AR-15s are classed as a Section 5 weapon (i.e. a person must provide an exceptional reason and gain permission from the Home Secretary, making ownership all but impossible for a private citizen.) However, AR-15s in a manually operated straight pull configuration or semi-automatic AR-15s that are chambered to fire a .22 rimfire cartridge are legal and can be held on a standard Section 1 Firearms Certificate. There are no restrictions on 'assault weapon features' in the UK, and no restrictions on magazine capacity. There are a number of UK manufacturers of "straight-pull" AR-15 variants. Southern Gun Company has tried to introduce a 9mm "self-ejecting" variant for gallery rifle shooting nicknamed the "Unicorn" but, despite numerous units being sold on the understanding that the rifle was a compliant Section 1 firearm, the rifles were seized and subjected to stringent testing by the UK licensing authority's Forensic Science Services (FSS). A small number of pre-production models were found to be non-compliant with section 1 status. However, later models were deemed Section 1 compliant and were returned to their owners.

Paul

[gitano]

From j0e_bl0ggs

Yeah, pretty much true only semi autos are rimfires inc. wmr etc.
Now there is a thought, 22WMR AR

[gitano]

Are you not interested in "pull-back" version in .17 Rem?

Paul

[gitano]

From j0e_bloggs

Would like the 17Rem in semi-auto but seeing that we are not allowed them the turn bolt will have to do!!!
Only straight pull would be a Heym SR30!

[gitano]

Note date and time on 'preferences'. I'll be coming back to those comments the next time I hear anything about a 'nail'. Whistle

Paul

[gitano]

I'm likin' this rifle!

I had to sight the 3-10x50 'scope in so I decided to do it with my first .223 reloads. Given the bullets and powders I have in hand, I went with a 55-grain Hornady V-Max, and a 69-grain Sierra BTHP MatchKing. The 55-grain bullet got 25.0 grains of Accurate 2495, and the 69-grain bullet got 22.33 grains of the same Accurate 2495.

The 55-grain bullet was predicted to be going 3004 f/s with a max chamber pressure of 47,808 PSI.

The 69-grain bullet was predicted to be going 2618 f/s with a max chamber pressure of 42,592 PSI.

Now that 2618 f/s is pretty modest for a .223 Rem, but I didn't want to push the pressure envelope. I'm not familiar with reloading semi-auto rifles, AND these were first loads. Both of the above charges are on a "timing node" for an 18" bbl. You will recall that I said that this barrel had a 1:7 twist rate. I was checking something else, and noticed that it is a 1:8, not a 1:7. I won't run the 55-grain bullet up to the next node, but I do have enough pressure head room to run the 69-grain bullet up to the next node. But let's look at the target...

I shot the 69-grainer first.


That little 3-shot bug-hole group is from the first three shots out of the barrel. I could hardly contain myself. It's been a REALLY LONG TIME since I've put three consecutive shots together like that, AND the first batch of the first attempt at working up a load! I got a little 'excited' and wasn't watching the barrel, and ended up resting the barrel on the rest instead of the floating handguard for the fourth shot. That is the lowest one. The fifth shot is the one up by the first three. I suppose I will SEE if the next node up shoots as well, but if it doesn't, I will be happy as a clam with this load.

Here is the 4-shot 55-grain group.


The 55-grainer gave me fits. Not the bullet, but the cases. Had a devil of a time getting the bolt to close completely on the case. As a result, I sent one of the 5 shots 'into space'. The other four aren't bad, but they had a hard act to follow.

It does appear that POI changes as the gun heats up. I'm not particularly worried about that as I could live with this rifle if it wasn't semi-auto. I expect it's use as a 'varmint' gun to be limited to one or two shots at a time with plenty of cool-down time in between varmints.

My first loads didn't work because I only neck-resized the cases I shot when I sighted in the other 'scope. Which reminds me, this is just "crappy ol' milsurp" brass. I bought a hundred cases of Winchester brass today. We'll see if there is any difference. Anyway, since I didn't full-length resize, the first batch of reloads wouldn't chamber. (It was a bigger mess than just "wouldn't chamber", but I'll spare you the details.) Suffice it to say that I won't be neck-only resizing for this rifle. I had to unload all the bullets and powder, remove the decapping rod from the resizing die, full-length resize, then recharge and reseat bullets.

I have always heard that one should FL resize for semi-autos, but I did't think it was an absolute. It apparently is.

More later.

Paul

[gitano]

From j0e_bl0ggs

Nice going.

FL size would be logical for semi-auto, you need chamber clearance for them to work.

Bet you were grinning from ear to ear with the first 3 rounds!

[gitano]

From DavidLT89

AND the first batch of the first attempt at working up a load!

boys, you gotta like that :D . God Bless.

[gitano]

From Jorge in Oz

Nice progress Paul, the AR15 is looking good and so is the shooting. well done. Must be satisfying seeing it all come together. Sorry i have missed so much, been busy with the little one.

Great project.

Cheers

Jorge
“The Germans brought the best hunting rifle to the war. The Americans brought the best target rifle. The British brought the best battle rifle!”



"Law and order break down as a direct result of placing political correctness above equity and truth" Mark Jenkins

[gitano]

From Nelsdau

Project is coming along, very impressive! That's a tough decision on cartridge choice. The ones you've got narrowed down I'm sure will all work. One factor I'm sure you are considering is how much time you want to invest in "making brass".

One thing I am curious about on subsonics in an auto-reloader is primer selection. Can you experiment with differing primers for the best burn in subsonic loads or does the AR platform limit what can be used?

Nels

[gitano]

To the best of my knowledge, Nels, there are no constraints on the type of primer one can use. However, I remain a novice with respect to shooting this firearm, but I can experiment. What are you thinking with regard to primer selection?

There are comments 'here and there' on the web about "turning off" the gas block when using the rifle in subsonic mode. I assume from that, that the shooters are operating in a "single-shot" mode. I can believe that some would choose that mode in order to truly minimize the "sound" of the shot including the noise of cycling the action which is not insignificant. Single-shot mode would be acceptable to me, however, purely from an "I want to know" perspective, I intend to work at getting the rifle to operate in subsonic semi-auto mode.

Paul

[gitano]

I've started a thread on the AR-10 build. The forum security won't allow me to insert the URL. Until I get that issue resolved, just look in this "Projects" directory. It is the only other thread.

Paul

[gitano]

From 22hornet

You have got to be proud of your efforts now that you are putting rounds on paper.
What is going to be your main projectile for this rifle?

[gitano]

Thanks 22hornet.

For the .223 configuration, the 69-grain Sierra BTSP is the one shooting the straightest, but I haven't spent much time shooting the rifle and only one handload bullet. Until I get some more trigger time, I'll be shooting the over-the-counter factory ammo from Federal that uses a 55-grain FMJ, or my reloads with the 69-grain Sierra.

My focus at the moment is 'making' the 8mm barrel with the 7.92x33 Kurz chambering. That entails:

1) Make the Kurz reamer,
2) Cut off most of the 8x57 chamber,
3) Ream the Kurz chamber,
4) Thread the stub for a barrel extension and "headspace nut",
5) Make the headspace nut,
6) Drill gas port,
7) Drill and tap the low-profile gas block to convert it to "adjustable",
8) Thread the muzzle for flash suppressor, and
9) PROBABLY put a "phosphate" finish on it.

Then I have to remove the .223 bolt from the Bolt Carriage and install the bolt that takes a .473 case head and make sure the headspace is correct.

I also need to get the CerraKote and go through the exercise of coating the lower receiver.

In the mean time, I have to take care of everything associated with the new boat, get ready to attend my eldest's college graduation, get her back here and help her buy a new car so she and her sister, (who will be arriving back from college a week later), can load it up and drive it 4,000 miles to Albuquerque, New Mexico where she now lives. And that's just up to May 28th. I'm not complaining, but my plate is fairly full, and the ARs are slipping down in priority. I'm still "on them", but they come second to other more time-sensitive matters.

Paul

[gitano]

New post in "Projects" on making the adjustable gas block.

Paul