I bought a USC/UMP conversion done by TE and the seller also sent me the left over parts from the conversion including the UMP fire control parts. I just want to make sure that I am not in possession of anything illegal here. One of the pieces included looks a lot like the friction sears used in the HK9x series, but it is made of plastic. Is that the "auto sear" part of the UMP? If it is, am I in any violoation of NFA rules? Are any of these parts contraband. I am not that familiar with the usc ump parts yet so I just want to make sure.