Do UMP mags fit into the stock USC receiver? I'm just wondering if I can make the UMP mags work by doing the mod to the upper and use the UMP mags for now until my UMP lower for my swap gets here.
*Post Edit*
Nevermind, I looked closer at the UMP and USC lowers. I figured it out.
*Post Edit*
Nevermind, I looked closer at the UMP and USC lowers. I figured it out.