MPI bolt carrier groups


So I was told by some friends the other day that if a bolt was MPI it would be stamped somewhere on the bolt itself. I have four different style bcgs and all say on the website that they’re MPI but there are no stamps on any of them. Any thoughts on the subject? I’m really curious about his now.


I have two that are stamped/laser engraved MPI on the underside of the bolt itself.


Mine (from PSA and aim surplus) are also engraved on the bolt.


All of APOC’s are marked. Most others that I’ve seen too.


I must not be looking in the right spot because I didn’t see a mark on my Apoc.


Apoc. 223/5.56 nickel boron.


AIM Surplus 7.62x39 nickel boron


I have four different bolts 1 Noveseke nitride that’s not stamped 1 Apoc nitride that’s not stamped 1 Wilson combat np3 that’s not stamped and 1 Wilson combat magnesium phosphate that has an M on it but that’s it and strangely enough the one stamped is the cheapest that I own lol