7.62/308 interchangeability.


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Lone_Gunman
December 7, 2006, 07:49 AM
How interchangeable are 7.62x51 and 308?

Can a Springfield M1A fire both 7.62 and 308?

Can a FAL?

Can a bolt action in 308 also fire 7.62?

Is there an example of a gun that is NOT interchangeable?

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Dr. Dickie
December 7, 2006, 09:24 AM
My understanding is that the differences in cases is irrelvent, it is the pressure concerns. That is, if your weapon was specially designed for 7.62 NATO, then you have to be picky with what .308 you run in it. However, the other way around is no problem (the NATO round being of lower pressure than the .308). And yes, you can run either in you SA Inc. M1A.

Clean97GTI
December 7, 2006, 09:28 AM
IIRC, a rifle chambered for commercial .308 will shoot either .308 or 7.62 NATO, but you shouldn't load commercial .308 in a weapon chambered for 7.62 NATO.

It might be OK for some rifles, by I wouldn't trust my safety to it. Maybe if I worked up some reloads for myself or had a smith check it over and make needed adjustments, but otherwise, no.

rangerruck
December 7, 2006, 10:03 AM
A well made commercial rifle, chambered in 308, should have no problem firing 762 nato, likewise a rifle designed for 762 nato , should have ho probs firing 308. Accuracy may be a little squirrely on the latter, though.

Rick O'Shea
December 7, 2006, 10:18 AM
Just finished reading about this on SurplusRifles.com; excellent article:
http://www.surplusrifle.com/shooting2006/308vs762nato3/index.asp

joebogey
December 7, 2006, 10:22 AM
One other thing, some single shot rifles such as the NEF may have a problem with 7.62 in that the ejector may not be able to pull the empty cases. I had one that shot great with 7.62, but I had to manually remove the cases. That was after having the breech reamed a little deeper and polished, and even replacing the ejector.
The only thing we can figure is that the 7.62 has a thicker case than commercial ammo.

MrDig
December 7, 2006, 05:21 PM
Does anybody know the pressure of a Mil-Spec HPT and or High Pressure Test round? Are people aware that while the Nato Standard pressure in 7.62x51 rounds are 50,000 to 55,000 psi, the weapons themselves are designed to handle significantly higher pressure up 67,500 psi. HPT Rounds fire @67,500 psi for a very specific reason, Due to the availability of 308 winchester ammo. D.o.D Specs require a soldier to be able to fire civillian ammo due to the fact that a soldier can scavange civillian ammo if need be.
This argument persists and no body ever makes the same claims about 5.56/.223 ammo. Why is that?
Do you honestly believe a Drill instructor would endanger a trainee by telling him he can scange 308 win ammo for his M60 machinegun? Why would the DI say that if it would kill or maime the Soldier. While hot bodies may or may not be expendable in wartime equipment isn't, the logistics of supplying a foot soldier and getting him an new M-60 and or SAW are next to impossible. Why would soldiers be Trained to risk damage to a weapon? (if you have served you know the military is almost if not more protective of equipment than Soldiers)
Everybody talks about the pressure of the rounds themselves and nobody talks about the max operating pressure of the Weapons. Why is that?
I am certain if they did it would destroy the credibility of an argument that says you should never fire Civillian .308 in a 7.62x51 mm weapon.

MrDig
December 7, 2006, 05:47 PM
I have a link and a quote to support some of the issues I raised in my last post,
first the quote
"The military 7.62 51 mm is nearly identical to the commercial .308 Winchester. NATO controls specifications for the military round while SAAMI controls specifications for the civilian round. The organizations have established two differences: the standard pressure is 50,000 psi for most military rounds, while the SAAMI maximum is 62,000 psi for the civilian round. The NATO M60 High Pressure Test round, is loaded to a pressure of 67,500 psi, so military arms should be capable of handling the pressure of civilian rounds The military chamber is specified to be 1.645 inches, compared to the civilian chamber of 1.632 inches, a difference of just 0.013 inches, but a chamber at the long end of acceptable military length will put excessive stress on the thinner civilian brass, causing premature head separation. To summarize, while it is not unsafe to mix .308 and 7.62 x 51 mm ammunition, fewer problems will be encountered if the correct caliber designation is used."
Now a link to the full Article
http://www.reference.com/browse/wiki/7.62_%C3%97_51_mm_NATO

Lone_Gunman
December 7, 2006, 07:30 PM
What non-Class III rifles available to civilians in the US are chambered in 7.62x51, instead of 308? I don't think I have seen a rifle chambered in 7.62.

TexasRifleman
December 7, 2006, 07:36 PM
I don't think I have seen a rifle chambered in 7.62.

My Fulton M14 was done with a 7.26 chamber reamer according to the manufacturer, not sure about the Springfield Armory versions.

hpg
December 7, 2006, 08:42 PM
They are the same....for all practical purposes and they will interchange...hpg

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