.223 or 5.56 ???

[SSgt's Son]

I generally don't read this forum, and apologize if this is something that has been beaten to death here, but is there a real difference in ammo identified as .223, versus ammo identified as 5.56? Read some comments on 5.56 ammo listed in Cheaper/than/Dirt, and those posts made it seem like there is a REAL danger in using 5.56 in a firearm identified as .223.

I thought that the ammo was the same. Would appreciate your comments on this.

Thanks.

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[hagar in SC]

Yes, it has been beat to death...

The only time it will be a problem, is when you shoot 5.56 loaded with heavy bullets in a bolt action 223 with a short throat. Any AR with a 1 in 9 twist or faster will shoot either just fine, so will a Mini-14.

[jjroth]

the 5.56Nato uses a thicker case than the .223, due to use in Class III firearms.

The NATO chamber is made to accomodate the heavier case. use of the .223 is permissible but reload life is shorten, due to the chamber being on the hight side of the tolerance range. Also the throat is longer (more freebore) than the .223 chamber.

Some sporting firearms have "tighter chambers' that will increase pressure higher than normal. So keep the 5.56 ammo use in a sporting rifle to a MINIMUM.

[Rick S]

Have a Savage 25 bolt action that will miss fire when using Federal 5.56. The primers are too hard for the firing pin strike on my rifle.

Rifle went back to Savage and ammunition went back to Federal. They came up with the diagnosis that nothing was wrong with the rifle, nothing was wrong for the ammunition, the rifle was not compatible with the ammunition.

[Mizzouboy]

Plus, NATO spec 5.56 is loaded much hotter than SAAMI (sporting) specs. Standard military loads reach pressures that are close to SAAMI proof load pressures. The increased freebore and bigger chambers in military arms helps reduce this effect, at a small sacrifice in accuracy but improved reliability.

[AKA Hugh Uno]

military CASES may or may not be thicker/heavier. some are, some are not.

military AMMO may or may not be loaded to higher pressures (and even when it is, actual testing shows it usually isn't significantly higher.

Velocity TENDS to run about 100 fps faster with SOME 5.56 surplus, but there is no way you are gonna be close to a "proof" load pressure. Maybe with a bolt gun from the early 60's and a SS109 green tip round JAMMED into the rifling would you get up to 60,000 psi (and I suspect proof is closer to 70K or more).

All AR and bolt gun manufacturers today cut chambers that EASILY accomodate ANY .223 or 5.56 ammo (including so called "match" chambers).

actual known "blow ups" of .223 rifles caused by MILLIONS of people shooting BILLIONS and BILLIONS of rounds of cheaper 5.56 over 40+ years = almost certainly ZERO.