Mil-spec .30-06 vs. commercial

[Doug444]

OK, I've done the search and found that the 7.62c51 Nato and the .308 Win. are not EXACTLY the same, and I understand the reasons why (mil-spec chambers NEED to function all the time). So, to be safe I'll use mil-surplus in my SA M1A and not worry about reloading for it. But what about those folks who have an M1 in.30-06? Do the military chambers differ from the commercial chambers the same way as the 7.62x51/.308?

Curiosity is an interesting thing.

 

[Grump]

There are no differences between military and SAAMI .30-06 chambers OR throats that I have heard of.

The military round was fully adoped before it was commercialized originally as the longer-necked '03 version. '06 was a change to a spitzer boattail bullet of substantially less weight (173 gr), and a shorter neck. Again, the commercial versions followed the military. I don't think that SAAMI standards were even around then--when did the club called SAAMI start? NATO was not even dreamt of in 1906.

Does your M1A have a SAAMI chamber or a NATO chamber? At the long end of SAAMI and the short end of NATO, they overlap. You *can* reload to SAAMI-min cartridge specs and safely shoot them in a long but not "field reject" NATO chamber, but expect only about three reloads before you need to toss the brass.

 

[Clemson]

But...., and this is a big but, M1 owners have to be careful about using commercial ammunition that does not match military pressure and burn rate specs. Slow powders will damage the action of an M1, possibly bending or breaking the operating rod.

Clemson

 

[30Cal]

The SA Inc rifles, as they leave the factory, are ok with both surplus and commercial ammo.

 

[Doug444]

Gentlemen, thanks for the replies. As usual, this is the place to garner such information. Heck, I can't reload for much less than I'm getting South Africal 7.62x51 these days.

 

[Publicola]

Actually there is a difference between a mil spec '06 chamber & commercial ammo. But the differenc i so small (a slight variation in the shoulder angle) that it doesn't affect anything.

Now mil-spec chambers are usually a bit larger than commercial chambers. It doesn't affect safety but it will shorten brass life. Mots mil-surp rifles were designed with slightly looser tolerances in the chamber to ensure reliable feeding. But it's no biggie except for brass life.

The big difference between mil-surp ammo & commercial ammo for the '06 is the powder burn rate. Mil-surp has a medium burn rate that is used not so much for chamber pressure, but gas port pressure. a really slow or really fast powder will cause excessive gas port pressure & could damage the op-rod of a Garand.

Now personally I only use handloads or mil-surp ammo in my Garand, but there are two commercial companies that make ammo suitable for the Garand. They are Federal (in their Gold Match line) & Black Hills (in some match rifle line they have). I wouldn't use any other commercial ammo - not even the American Eagle stuff - in a Garand because the velocity indicates that it's a bit hotter than mil-spec & probably (almost definitely) is using a slower powder which could push gas port pressures beyond what's cool.

& yes, I know that a lot of people having been using 180 grainers loaded to commercial specs for a long time in their Garands & haven't had a problem. A lot of people like catching a wheel in 2nd or powerbraking when tey leave their friends house. I don't like buying tires or op rods so I try to stick with the ammo the garand was designed for. Or more appropriately I stick with ammo designed for the Garand.

Of course if you have an adjustable gas system then that's another ball of wax...

But yes, there is a difference between mil-surp & commercial chambers, but it's so small that it doesn't affect anything except a gun owners version of trivial pursuit.