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[usmc0341/8531]

Can all colt military style rifles fire 5.56 even though it is labeled .223 on the magazine well. The gun shop owner told me that even though it is listed as .223 cal all military rifles (Colt, Bushmaster, etc.) are chambered for both cal.

I know that if it is chambered for 5.56 you can shoot either, but if it is .223 you can not shoot 5.56.

[dfariswheel]

I've heard that Colt uses a chamber that can handle both.

To get the final word, just call Colt and ask them.

[akviper]

All Colt brand ARs were chambered to 5.56mm specs. Not so with some of the other AR builders.