Hi all, wanted your opinions on how difficult it is to convert a USC to be able to accept UMP magazines. Also would this be legal? To alter the lower of the USC? Any thoughts are always welcome. Many thanks,Cj
Its called a UMP conversion. Pretty easy to do. You need a UMP lower. Ump stock block and a ump stock and pin. 3 US made parts to be 922r compliant. Hammer , trigger and sear. Look up Tommybuilttactical.com You can buy a US made ump receiver.
It’s pretty easy but costly I just did a conversion and it cost around 1200. I don’t believe you can fit a ump mAg in a usc lower without adding material to the outside first though if that’s what you really want. Also 20rd single stack mags are available.