Originally Posted by
t15
OK, got to the range today and here are the results. Before going, I replaced the gas rings with new BCM ones, no other changes made, no effect on performance-still jamomatic.
Replaced the extractor spring with a new BCM unit and also replaced insert, still jammed. Installed rubber O ring and 60 trouble free rounds!
The BCM BCG that came with the upper had their CS 4 coil? spring installed and no O ring, it was identical to the ones in the multi-pack I had that said you may not even need the O ring on the packaging. I am wondering if anyone else has had to install an extra power spring or use O ring on their short barrel to make it function?
I am going to check the DD and friends BCM bolts from the OP to see if they had O rings or not. If they don't and were running OK without O rings, I guess I will still call BCM?
edit: I am curious if anyone is running an SBR with BCM's enhanced CS spring and insert, but no O ring.