*Sigh* So which AR should I get?

[Fatman]

Well, half true TAB. There is a difference in case thickness, but all NATO and commercial .308 are otherwise the same except for pressures.

Now, the important part. From what I've read, the NATO chambers can be longer and that meets milspec. The heavier case prevents problems here. If you check your NATO chamber with a .308 field gauge, and it swallows it, that NATO rifle cannot safely shoot the thinner commercial .308 and you must check it with a NATO no-go gauge and field gauge to see if it is still ok for NATO ammo. If it fails the field gauge, it's a wall-hanger.

Essentially, all in spec .308 chambers can shoot NATO, all in spec NATO may be able to shoot .308

http://armedcanadian.blogspot.com/2007/11/shooting-308-out-of-762-nato-chambers.html

Crap. Now you've got me thinking on .223 and 5.56 chamberings, and I gotta go to sleep. Grrr.

[MikeBjerum]

If I understand the last few posts, you either buy and shoot .308 or you buy and shoot 7.62, but you do not interchange.  Correct?

[Rastus]

Excellent Fatman.  I learn something every day...

[Pathfinder]

If I understand the last few posts, you either buy and shoot .308 or you buy and shoot 7.62, but you do not interchange.  Correct?

Everything I've seen or read indicates that the .308/7.62 issue is not significant - case sizes are not different, and pressures are not an issue either. The .223/5.56 issue is significant - case sizes can be as much as .01 off, and pressures can be very different. If you load, go with the ranges and powders indicated, don't try to over-load.

But then I never worry about it, as all my goodies are marked either 5.56 or 7.62 which is the safe way to go.

[m25operator]

I have to disagree, if your shooting and M1 or M14 derivative, although the action will take SAAMI spec .308, or 30-06 , meaning it won't blow up, but the extra pressure of SAAMI spec stuff, will bend and damage the op rod, and lead to failures.

[Sponsor]

[Hazcat]

SAAMI specs are lower than military specs per American Rifleman Feb 08 issue.  If it will shoot 7.62 it will shoot .308 just fine.

Now the .223 vs 5.56 thing was due to chamber size.  Military being looser as many diff producers of ammo in many counties with less than perfect (or even good) quality control.

Pressure was (and is) not a problem.

[MikeBjerum]

So now I'm back to 7.62 and shoot whatever I want; 5.56 and shoot either, but reload my own for accuracy; and .223 for real accurate .22 caliber.

Bigger problem is priority ... I've got $1,500 burning a hole and might not be able to say if I oops today there is always six months from now (got a couple "fun" guns in the rack that way already).

[tombogan03884]

I have to disagree, if your shooting and M1 or M14 derivative, although the action will take SAAMI spec .308, or 30-06 , meaning it won't blow up, but the extra pressure of SAAMI spec stuff, will bend and damage the op rod, and lead to failures.

7.62 and .308 are  the same and ARE interchangeable, As Haz points out SAAMI specs are lower than Military. If you are shooting .30 - 06 in either caliber rifle you will wreck the rifle and hopefully hurt yourself because stupid should be painful. .30-06 while it uses the same BULLET is a completely different caliber that should not even FIT in a 7.62 or .308 chamber. No wonder you had a bent op rod 

[m25operator]

All right go ahead and shoot .308 anything in your M1a, it will bend the op rod, and that has to be fitted to the rifle, by someone, like ME. Go ahead and shoot SAAMI 30/06 in your garand, the same thing will happen, they were not meant for those pressures as issued, there are devices you can install to adjust the gas regulation, and make it ok, but as issued will take a beating.

Maybe the SAAMI ratings have been lowered, they definitely don't email me about things like that, to take into consideration things like M1a's or Garands, but when I bought both of mine, it was warned against, and my rifle coaches agreed.

[tombogan03884]

All right go ahead and shoot .308 anything in your M1a, it will bend the op rod, and that has to be fitted to the rifle, by someone, like ME. Go ahead and shoot SAAMI 30/06 in your garand, the same thing will happen, they were not meant for those pressures as issued, there are devices you can install to adjust the gas regulation, and make it ok, but as issued will take a beating.

Maybe the SAAMI ratings have been lowered, they definitely don't email me about things like that, to take into consideration things like M1a's or Garands, but when I bought both of mine, it was warned against, and my rifle coaches agreed.

I misunderstood, thought some one was trying to cram 06 into an M 1a