traded an sks for what i was told was a brand new never fired colt ce1000 expanse with added fwrd asst and dust cover... i have never seen this mark on an upper receiver and i have searched and googled for about 12hrs and cant identify it. also the barrel is marked 5.56 NATO 1/7 P not 5.56 NATO 1/7 C P like others i see online. gun does look brand new and the upper fits lower perfectly everything about the barrel looks like the expanse except no C stamp. hoping someone can help me find out if i was ripped off or if some of the expanse M4 models were made like this. the BCG is stamped MP and looks just like the one in my 6920 just slightly different shade and not marked mpc.