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Rem 700 action how much chamber pressure is safe?

 
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  #8  
Old 03-17-2009, 08:43 AM
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Re: Rem 700 action how much chamber pressure is safe?

I don't think it's safe to load or use ammo with peak pressures getting even close to the action's limit. The reason is the case is weaker than the action and it'll have problems long before the action does. I read some years ago that the Rem. 7XX actions were good for about 130,000 to 140,000 pounds psi (impulse pressure, when fired) before bolt lug setback started.

Cartridge brass starts to extrude at about 75,000 pounds psi (about 65,000 cup). If the case head starts extruding back into bolt face cut-outs, I think one has two choices:

* Reduce the load (less powder, lighter bullet, etc.) and shoot safe.

* Satisfy your egos and use that load (or a heavier one) and shoot happily and dangerously.

Therefore, I think one should limit chamber pressure to what the case safely allows, not what the action does.
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  #9  
Old 03-17-2009, 08:52 AM
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Re: Rem 700 action how much chamber pressure is safe?

The custom receivers may appear to be the same as the Rem 700 but they certainly are not where it matters. They have longer, wider and thicker bolt lugs that have a much higher shear point.

More importantly, they will have more steel behind the bolt lugs in the receiver. May only be 50 thou thicker but this is a dramatic amount when it comes to strength.

Also, many of them have slightly larger receiver threads so that the barrel threads are larger in diameter which also helps control any stretching of the chamber area when fired with a larger diameter chambering.

Again, they may appear to be the same but that is externally.

Another thing to consider is that you can manipulate heat treating and use different materials to make a very similiar product much stronger. There is much more then meets the eye with most of these custom receivers.
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  #10  
Old 03-17-2009, 09:39 AM
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Re: Rem 700 action how much chamber pressure is safe?

Thanks for the info Kirby.
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  #11  
Old 03-17-2009, 09:53 AM
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Re: Rem 700 action how much chamber pressure is safe?

I stoped loading maximum load years ago because of the problems encountered
with it.

I use a different approach to more velocity without more pressure ( A bigger case )
and slower powder with a longer barrel.

With so many choices there is no reason to push your equiptment or your luck.

And the only reason other than Kirbys is if you open the bolt head up to far you
all but eliminate the ring/shroud around the case head that protects you from
a face full of high pressure gas from a blown case.

If you take your car and put it on a track and drive it wide open you woun't get far
but if you drive it like it was designed for it will last many miles.

Same thing with a firearm.

Also factory rifles have a 50% safety factor biult in and as you go above the designed
pressure you eat into this very fast.

Good Post Kirby you explained it very well

J E CUSTOM
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  #12  
Old 03-17-2009, 10:31 AM
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Re: Rem 700 action how much chamber pressure is safe?

This is great info. Brings me to a question. How does one know when he is at max pressure when loading a wildcat based on a Lapua case? My question more specifically. I have a 30-338Lap imp built on a Sako M995 action. There is no load data to reference. I back my loads off from any kind of sticky bolt, but the case is pretty straight, so I experience some stickiness on the initial lift, but not beyond that. I feel like I run it pretty hard, but I really don't know. I have used Kirby's numbers for his 300AX as a guide line, but after reading his post here, I have some doubt. I had always thought that the Sako action was the heaviest factory action.

Sorry about the hi jack, but I would sure like to see more input if anybody has more to share.

Thanks, Steve
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  #13  
Old 03-17-2009, 11:47 AM
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Re: Rem 700 action how much chamber pressure is safe?

One thing I did when developing my wildcats based on the 338 Lapua case was to do some load development using the Norma made Lapua case which is a great case but much softer then the Lapua and it will tell you more about chamber pressure then the Lapua case.

In fact, the Norma cases are very similiar in hardness as the Remington RUM cases. Good cases and they will certainly tell you when your over the top.

I then used that data as a baseline for top end loads even when using the Lapua case.

Basically, look at the chambering your using, compare it to similiar chamberings and you can basically figure out where you should be. In your case, you have a 300 Lapua basically.

If you look at the parent case, the 338 Lapua and compare it to a 338 Edge, the performance is nearly identical with the Lapua maybe getting a 50 fps boost in performance, MAYBE.

With that in mind, you know what to expect comparing the 338 Lapua to the 338 Edge which is basically the 338-300 RUM.

If you know that, you can expect that the 30-338 Lapua will basically get you the same performance as the 300 RUM, again, perhaps 50-75 fps more.

Now if you have an improved version, you will get 100-125 fps more then the RUM. You just have to take a realistic look at whats out there with similiar case capacity.

If your getting 400 fps over what the 300 RUM will get you, obviously, your overloading the 300-338 Lapua. Just need a realistic point of view and some common sense. That with the help of a chronograph and you will be in good shape.
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Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
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  #14  
Old 03-17-2009, 12:04 PM
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Re: Rem 700 action how much chamber pressure is safe?

Thanks Kirby.

I have also paid attention to the 300RUM as a guide line. Have always stayed within 150fps of the RUM. Considering my barrel is 30" I think I am ok.

Thanks again Kirby. Hope things are well for you.

Steve
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