Mark, yes, the M&P sport 2 is chambered in 5.56. so it will safely fire both 223 and 5.56. you just can't shoot 5.56 out of a firearm chambered in 223 because 5.56 has a higher chamber pressure. Hope this helps.

Mark, yes Sir. The barrel is stamped 5.56NATO so it will fire both 5.56 and .223 in any sequence on issue. Cheers and stay safe!

Mark, you certainly can. The M&P Sport II will fire either with no issues. You can load your magazine alternately with both .223 & 5.56 at the same time if that's what you want to do. Have a great day!