[Naphtali]

Recently I was informed that while 7.62x51 mm NATO and 308 Winchester cartridges look, to the eye, to be the same, they are not. Also, their chamber specifications I was informed are different. Are these statements accurate?

If they are accurate, does one of the two cartridges become marginally safe when fired in the other's chamber? If this is true, which is which? Were I barrelling a rifle and wanted to assure that whichever cartridge was fired in the rifle was absolutely safe, which [cartridge] chamber would I choose?

[rcmodel]

The cartrides are the same.
They use the exact same reloading die to size cases back to spec.

The 7.62 NATO chamber is slightly looser, with a longer leade to insure functioning in dirty combat weapons.

Commercial .308 ammo may be loaded to higher pressure then some 7.62 military ammo and should not be used in some military rifles.

7.62 NATO ammo is safe to use in any .308 Winchester rifle.

See this about that:
http://www.fulton-armory.com/308.htm

http://www.thegunzone.com/30cal.html

Bottom line is, if you are re-barreling a bolt-action .308 Win rifle, you want a .308 Win chamber to fire .308 Win ammo in..

If you are re-barreling an M1A or AR-10, you probably want a 7.62 NATO chamber.

rc

[Backpacker33]

I JUST talked to Springfield Armory because their new rifles come with a warning about that.

"Patty" in customer service said that commercial brand name ammo is OK. She said to be cautious with ammo that is hand-loaded or from unknown commercial loaders, because headspace is critical and some reloaders don't consider it carefully enough. The note with my rifle had the dimensions of my particular serial numbered gun's chamber on it!

I will say I've used a lot of NATO ammo over the years and had problems only with some that came from Greece. One actually blew apart in the chamber, causing me to send the rifle back to Springfield to be checked. It was fine and I dumped the rest of that ammo. Just to be fair, I know other shooters who said the Greek stuff was the best of the older, expired NATO 7.62 ammo.
- Backpacker

[rcmodel]

Well, apparently "Patty" doesn't know about Hornady Light Magnum .308 ammo then.

It develops considerably more energy / velocity then standard commercial .308 hunting ammo by using a slower burning powder then is normally used in .308.

I think it shouldn't be used in any gas-operated firearm.

rc

[BBBBill]

...Well, apparently "Patty" doesn't know about Hornady Light Magnum .308 ammo then.

It develops considerably more energy / velocity then standard commercial .308 hunting ammo by using a slower burning powder then is normally used in .308.

I think it shouldn't be used in any gas-operated firearm..

Certainly not in an M1 or M1A! :uhoh: I see (at least) bent op rods in the future for anyone who does.

[kenno]

It's still SAMI spec

[rcmodel]

It's SAAMI spec for Max chamber pressure.

But it's not to anyones spec except Hornady's for bore pressure and how much there is at the gas port on a gas operated firearm.

I stand by my statement that I would not use it in a gas operated firearm.

Hornady even said the same thing on the ammo box.

And they say this now:
"Superformance is also friendly for use in all guns, including semi-autos, unlike Light and Heavy Magnum that had a pressure curve that wasn’t conducive for use in semi-autos.” – Jason Hornady, Vice President/Director of Sales."

rc