2 dumb questions

[Bart B]

Originally Posted by Loner

You do not shoot bolt gun .308/7.62 loads in a gas gun. As stated .308 and 7.62 are
the same. 5.56 and .223 are not. The shorter tighter throat on a .223 can pinch the
bullet as the brass stretches into the throat. I don't think it has ever been a problem in
a bolt gun but it has been in an AR.

I and a few dozen others I personally know have shot thousands of rounds of commercial .308 Win. ammo in US military semiauto rifles.

Why did the US military rifle teams shooting both M14's and M1's with 7.62 NATO mil spec chambers order then shoot millions of rounds of commercial .308 Win. ammo from Remington, Federal, Hornady and Winchester ammo without any signs of a problem? And after the M16 was first allowed for use in competition, millions of rounds of .223 Rem. commercial ammo was bought from the same companies to shoot in them; all without a problem of any kind. All the service teams shooting competition-grade M16's it's first year (1971) used standard commercial .223 Rem. cases to hanadload their ammo with.

This absurd issue came up one time some years ago when I was on a military team, so I called Springfield Armory in Massachusetts to ask them about this. Their engineer told me commercial .308 Win. ammo was safe to use in both the 7.62 NATO barrels they made for Garands and M14 rifles; they knew the military teams were doing it and had no safety concerns whatsoever.

Even Remington's Mike Walker, the guy who headed the design team for the 7.62 NATO round knew it was safe to shoot commercial ammo in the military chambers. He tried to convince Remington to make it a commercial round so it would be just like the .30-06; swap ammo types between both comerrcial and military firearms. But Winchester beat out Remington for the commercial version as they got the first really big military contract for 7.62 NATO ammo.

[CogburnR]

The leade or throat of the 5.56 is longer and the actual 5.56 ammo for it is hotter than 223 to take advantage of the longer throat.

If you shoot 223 in a 5.56 it is ok because the 223 is made for a shorter throat.

If you use 5.56 that is really 5.56 in a 223 you may have pressure problems because of the short throat and the ammo is made to produce full pressure in a long throat gun.

[etisll40]

Thanks, I have to get one of my ar-15 barrel's checked out as I don't know what it was reamed for?

[CogburnR]

Michiguns offers a gauge to check your chamber.
223/5.56? Gage


Michiguns Ltd. - AR-15 Tools and Accessories

[meatyrem]

Loner and cogburnr are on track with what I have found too. There is a difference in the throats between the 5.56 and the 223

[etisll40]

I should buy the gauge, I've been reading that unless you check yourself, you might get a barrel you may not want.

Thanks

[Wile E Coyote]

Originally Posted by CogburnR

The leade or throat of the 5.56 is longer and the actual 5.56 ammo for it is hotter than 223 to take advantage of the longer throat.

If you shoot 223 in a 5.56 it is ok because the 223 is made for a shorter throat.

If you use 5.56 that is really 5.56 in a 223 you may have pressure problems because of the short throat and the ammo is made to produce full pressure in a long throat gun.

I agree, Loner and CogburnR have said it best, at least as I understand it regarding the mentioned chambers.

I hope I don't confuse this any more but this thread made me look at My AR, a Rock River Arms. Check to see if your 5.56x45/223 AR has a ".223 Wylde" chamber. The wylde chamber will handle both commercial and military cartridges. My gun is stamped "5.56mm" but in RRA's spec's it's a wylde chamber. I've shot both from the gun and no problems. It is my understanding that the wylde chamber was developed to resolve the issues with chamber specs involving 5.56/223

my .02