How do you tell BCG brands apart!?

AR/M4 AR Technical Discussion
1

I just ordered and received an LMT F/A bcg. While I’m not doubting it’s authentication, how do you tell the different brands apart? It looks identical to my F/A CMMG bcg yet costs quite a bit more. I noticed some BCM’s say so on the side and I thought LMT’s did as well. Maybe I saw a pic of their enhanced version or possibly it was marked for photo purposes.

2

Usually the markings on the bolt, and sometimes the markings on the bolt carrier.

BCM starting laser engraving their carriers, and Colt has C stamped on the side as well as MPC on the bolt itself. LMT should have a 2 letter date code on the bolt unless they stopped doing that.

3

Thanks for the reply. Mine says MP on one side and AT on the other of the actual bolt itself. Nothing what so ever on the carrier.

4

My recently purchased LMT with standard FA BCG has MP and AL stamped on the Bolt.

5

LMT bolts have an undercut at the rear of the locking lugs and some carriers have a MIM gas key.

to my knowledge, the regular FA/SA carriers are not engraved with any other identifying markings. I believe they may use a unique type of hex head screw to secure the gas keys, it’s been a while since I’ve paid close attention.

6

I’ve ordered LMT bolts and carriers over the years that had no markings at all. Not sure it mattered but for what it’s worth I now order either DD or BCM’s exclusively when building for myself or friends.

7

Yeah the AT is the two letter date code.

MP is magnetic particle testing. Its a way to test for any issues with the bolt like stress fractures.

If it came with some brass marks on the bolt face that is a proof load testing. Ideally the BC is fired with a proof load (a high pressure load), and then tested. The high pressure round helps expose any issues. Some people think they got a used BCG when it shows up with brass marks on the bolt face…

8

Very easy. Every BCG has a “tell.” For LMT, it is their MIM gas key and the screws they use. You can also look at the bolt and see dual letters stamped on it.

You can also tell by the extractor spring and extractor insert (in a lot of cases).

C4

9

Doesn’t CMT make 90% of the industry’s bolts? Seems like the economies of scale really kick in- you have to machine a lot of really hard steel to make a $50-70 bolt.