Milspec Carpenter No. 158® Steel
I have a BCM upper and it is the best one I own. So I thought a BCM bolt would also be good. These are a great bolt. Shot peen, MP test, top military quality stuff! Super strong extractor - the way it should be. Great job (again) to the team at Bravo!
This is a quality bolt after doing some checking the MP stamped on the bolt leads to the LMT Lewis Machine&Tool Co. one of the leading US Government contractors. It comes with the black incert in the extra strong extractor spring and has the Crane black O-Ring that can be installed.
This is a very nice, very high quality, shot peened bolt.(Colt Quality IMO) The included extractor spring is so strong(the strongest i've seen) that a Crane O Ring or D Fender isn't needed, but included.(the Crane O Ring).
Buy with confidence.