.223 or 5.56?

My new bushmaster says .223-5.56 on the reciever. But it also says 5.56 NATO on the barrel. I know it will shoot both, but what ammo was it made for?

Either 5.56 nato and .223 have the same external dimentions but 5.56 runs at higher preasure levels.

You can shoot either...If marked 223, you can only shoot 223.

5.56 may show signs of excessive pressure and could damage the gun.

Shoot military 5.56x46 and enjoy relatively cheap shooting.

x2

Thanks guys!