Yea, in fact I got the receiver back this last Tuesday. I didn't have a chance to update this forum yet. They sent me a label, got it cleaned up and sent it back to me. The only thing is it took another 3 weeks, to get the receiver back. They even threw in a trigger shoe free.
I reassembled the M4 and its works great. My next project is try to fix the shell catch, I tried quad loading and I can barely push 1 shell in without the 2nd one popping out...