The .17 Predator on a Savage Axis Action

[gitano]

A 28" bbl is certainly a long one. farmboy, you might be interested in this thread regarding barrel length and muzzle velocity: http://thehunterslife.com/forums/showthread.php?t=3050

Lots of computer troubles "going around" these days its seems.

No sweat, Paul H., I'm finished reaming chambers for the time being, but thanks for the offer!

I worked 6 hours on the fire-forming device today. Got at least two more hours of work. I have yet to make the firing pin. I have the 'receiver' made and threaded to accept the "barrel" (die). I have made the "breech block" and threaded both it and the 'receiver' for it to screw on. I have some 'cleaning up' to do and some holes to drill for the body of the firing pin and the firing pin hole in the breech of the receiver. I can't get the pictures off of my phone until it charges.

Paul

[drinksgin (deceased)]

Sounds very similar to the "universal receiver" some of the cos. use to get loads worked up.
I did know one person who used a Lee eng. whackamole die to fireform a cartridge.
He just put a punch on the primer and hit the punch with a hammer.
I only watched him once!

[Paul Hoskins]

Paul, after thinking about the chambering problem I've come to the deduction the problem was work hardening. This is caused by a tool sitting against a metal object with too little pressure on it. Chrome moly steels will do it but the worst offenders are the exotic metals like hastelloy, titanium & other metals with nickel content. If you had thought in time & ran a .312 drill bit in just a few thou. it would have broken up the hardened surface at the shoulder & allowed the reamer to cut again in it's normal fashion. .....farmboy, to answer your question on barrel length, My 17 Rem. & 17/225 use 24 inch barrels. The only 17 Ackley Bee I have left has a 22 inch barrel. ......Paul H

[farmboy]

Yes i have read the tread on barrel length. I am a believer in long barrels and slow burning powder with heavy bullets. I see some do not go with that theory which is fine but the one thing that is really right bout long barrels is less noise and muzzle blast.

[gitano]

Excellent point, Paul. That explanation fits all the observations.

So I finished the fire-forming device. 12 hours in the shop, and a couple more 'designing'. In the end, it doesn't work. Pretty annoyed by that. Actually, it "works", but it doesn't WORK. Here's what I mean by that. In a rifle, the extractor claw holds the case against the bolt face so the primer can strike it. This device has nothing to hold the case against the "bolt" face. The headspace datum point (about the middle of the shoulder), doesn't exist yet. That is in fact the purpose of fire-forming. In this case, the case falls into the "chamber" because there is nothing to stop it. I was able to perform a function test on the firing pin protrusion by holding the case against the "bolt" with a cleaning rod. Doing so allowed me to tap the firing pin and everything worked as designed. In other words, the firing pin ignited the primer.

I'm not sure what I can do to hold the case against the breech. I was thinking about an o-ring in the extractor groove. Kind of a pain to install and uninstall for every case, but at the moment I don't have any other ideas.

Here are some pictures. Usual caveats go with cell-phone pictures.

Here is the "receiver". The end toward the tail-stock is the end that receives the "barrel". The narrow part is the part of the device that captures the firing pin. You will see it later, threaded.


The shoulder you see is a stop for the 'hand guard' which is a 2" aluminum pipe.




Here it is after threading 7/8ths-14 to match die.



Here is the back part of the receiver that captures the firing pin. The part is to the right of gap. The gap is what I had to do to part the piece off. None of my parting tools were hard enough for this steel. Lotsa waste. This part screws onto the 'receiver' - 1"-12 threads - internal for this piece, external for the 'receiver'.


Once the 'receiver' and the 'cap' were threaded and 'timed', each needed to be drilled for various parts of the firing pin. The firing pin has three diameters: The "pin" which is 0.092"; the body which is 0.375" (3/8ths); and the "striker" 0.250", which is what I whack with the hammer. The lengths of each of the three areas has to be precisely fitted to the cavity in which the firing pin resides. The pin needs to protrude into the 'chamber' between 0.050" and 0.060". Therefore, the front shoulder of the firing pin - the transition between the pin and the body - has to be located such that when it strikes the front of the chamber that holds the firing pin, the firing pin extends into the chamber 'just enough'. The precision of the location of the rear shoulder of the firing pin - the transition from the body to the "striker" - isn't as critical as the front shoulder. However, it shouldn't be too 'sloppy'. The next picture is the start of the drilling of the holes for each of the parts of the firing pin. Each hole was 1/64" larger than the part. What you are seeing is the "cap" screwed onto the "receiver" with the receiver held in the chuck. The drill is a 3/32" (0.09375"), hence the need for the firing pin to be 0.092". Drilling both the 'receiver' and the 'cap' at the same time means that  all holes are perfectly aligned.

I would note that this is the "starting" hole for the cap. That hole is ultimately, 0.2656" (1/4" plus a 64th).

Here is a picture of truing up the aluminum 'hand guard'. These pictures are for j0e_bl0ggs that doesn't believe I use steady-rests.




Here is a picture of all of the finished pieces except the hand-guard. On the left is the chambered die - the "barrel"; then the 'receiver'; then the firing pin; then the 'cap'.


This picture is of the firing pin inserted in the "receiver". The 'cap' is to the left.


Here are the three pieces together.


And here is the whole assembly with the hand-guard in place.


Have to figure out how to make it WORK now.

Paul

[farmboy]

this might be a dumb idea but could you mill the end of you barrel part and make a fork that slides into the extractor groove of the case  if the fork held  half of the circle would that be strong enough?

[gitano]

A 16th of a circle would be enough. The problem is that the case isn't loaded from the breech/rear, it's dropped in the "barrel" (die) and then screwed into the 'receiver'. Therefore, anything that would be made to hold the case would have to NOT impede the threads/screwing.

But... especially because you are relatively new here at THL, PLEASE don't hesitate to offer suggestions! That is in large part why I make these posts. Everyone's input is solicited AND appreciated!

Paul

[j0e_bl0ggs (deceased)]

With your partially sized brass it should be a 'crush' fit to the 'breech' face, is this not the case?

[gitano]

No, and it's not in the rifle either. In the rifle the extractor is holding the case in place for fire-forming. A neck-sized .223 case 'drops' in - significantly - past the breech of the barrel and the die. In the rifle, it's the extractor holding the case. In the fire-forming device, there is no 'holding in place'.

Paul

[j0e_bl0ggs (deceased)]

So in initial forming of the case the provisional neck is too far back. It should be registering on the false neck/shoulder junction and base should be flush with the die.

[gitano]

Base is flush with die. "False" shoulder is not a shoulder for the die chamber OR the rifle chamber. There is NO contact with the front of the chamber either in the die or in the rifle, even though in the die, the case is in the chamber the extra distance of the extractor groove and rim.

Paul

[j0e_bl0ggs (deceased)]

There should be contact of the 'false shoulder' summat wrong here maybe need draw up how it should be.

[22hornet]

I would have thought a false shoulder would have been the way to go too.

Back when I had my .243 AI, when fireforming I had to neck up the brass to .25 cal then back to .243 leaving a false shoulder. Often enough the extractor wasn't enough to hold the case in position and the case was pushed furhter into the chamber by the firing pin. The false shoulder fixed that problem. :grin:

[j0e_bl0ggs (deceased)]

In both cases, die or rifle the 'False shoulder' is the important bit!


Please excuse rough dwg.
Point I'm trying to make is that this shoulder will support the cartridge in the chamber.
There is no need for it to be supported by the extractor. the 'crush' is between this and the case base.






...

[gitano]

I knew exactly what you were referring to. However, reality rears its ugly head. That is NOT how it is. Neither in the rifle or die.

Paul