Ive posted before about Sig's mpx carbine. And though it looks like a gun ide buy, sig might not sell the thing due to the atf. So that brings me to my next purchase/build. Im looking for a rifle like the mpx. Or an ar-15 in 9mm or 223/556, sbr, extended hand guards that come just shy of the end of the suppressor. So all you ar experts steer me in the right direction. Should i go 9mm or 223/556? Not looking for long range. Max of 100 yrds. Mainly just a fun gun. But i also want this thing to be lethal enough in a home protection situation. Ideal ar build 223/556 or 9mm The mpx carbine that ide like to replicate the idea. Shoot Strait!