Just received a new M16 bolt carrier. There is a “C” on the left side of the carrier and an “MPC” on the bolt itself.
There is a blue extractor insert? I thought all auto BCG’s have a black one? Maybe it’s a take off from a rifle length gas system? Or was this how colt used to put their BCG’s together?
The carrier + bolt appears new.
Not really an issue, I just wanna know a little bit more about BCG’s.
From my understanding, the blue insert is standard for rifle length gas systems. I have 3 M16 BCG’s (2 BCM’s and a G&R) though, and all 3 came with the black insert. So I don’t know… Someone who knows more than me will be along directly to clear it up I’m sure.
QS,
Generally speaking a blue insert is indicative of it being in a rifle. It’s also possible that someone swapped the extractor spring/ insert or that the BCG has been around for a while. Just get a carbine type spring and insert and you should be good.
Will do, I was gonna use it in a mid-length upper anyway. There is a “C” on the inside of the extractor. “C” = Colt?
The bolt also has these weird cuts behind the lugs, like the bottom bolt in this picture (NOT MY PICTURE).
Anybody know the purpose of these cuts? 
What is the “T” all about? Maybe this is actually an LMT bolt? Looks like the bolt has seen some usage or maybe it’s the pics. Not sure if those cuts are just from machining or if they are something else.
I think that IS an LMT bolt. Not my picture, just borrowed it to show the cuts on the Colt bolt on the bottom.
Sorry for the confusion.
The top one is LMT as can be seen by the patented relief area behind the lugs.Plus the letter “T” stamped on the bolt.I have LMT bolts stamped AB,AC,T,Z.Im not sure but LMT must use the letter codes as lot# or an inspectors stamp etc…Grant or some of the others here may have more information on that.
The bottom bolt is identical to the bolt that is in my brothers rather old Colt.I have no idea about the small angled cuts at the rear of the lugs…maybe some kind of relief cut for the lugs.
If you score an old M16A2 or M16A1 bolt group, it’ll likely have the blue insert. CDNN used to sell a shitload of these. I don’t think there is a conspiracy to jip you out of a $4 part.
Just swap it for the black spring/insert.