AR Build - Moved from Biopar Site

[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.