556 only shots 556. If you get it chambered for 223 it will shot both. The difference is in the throat.
English
-
never shoot 556 through 223. upper isn't rated for the pressure.
-
Gotcha. I thought it was the other way around.
-
It is.
-
Hell, i could be. Its been so long since i built mine i honestly cant remember. Guess i should google it.