Why would you want a .556 rifle to shoot 9mm? I mean that as a serious question.
If your rifle is barreled for .556 then it should also be able to fire .223. When the zombie apocalypse happens id rather have a rifle that can cycle two types of ammo. Lol.
English
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.556 is not .223....5.56 mm is not the same as .556. The closest to .556 would be the boyse (spelling) British antitank rifle from WWII.
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556 only shots 556. If you get it chambered for 223 it will shot both. The difference is in the throat.
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never shoot 556 through 223. upper isn't rated for the pressure.
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Gotcha. I thought it was the other way around.
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It is.
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Hell, i could be. Its been so long since i built mine i honestly cant remember. Guess i should google it.