That’s very interesting for me. I have maybe a dozen rifles running BCM bolts, 4 of them SBRs, and have had zero bolt or bolt carrier related issues over 10+ years. Oldest one is more than 15 years old at this point, and has had the rings, etc. replaced at least 4 times…may have even swapped in a new BCM bolt at some point, but honestly don’t recall.
Those guns all get between 1-2K rounds run through them every year (each). Not a heavy firing schedule by any means, but enough to reveal any major issues for sure. We switched all the ranch guns to BCM bolts specifically because we saw some issues with other brands, and the BCM bolts just plain worked.
I wonder if BCM had a bad run of keys, or if the flat area where the key sits on the carrier wasn’t machined flat, or hell, maybe something as dumb as not being torqued to spec. Regardless, if you had that many issues, that points to a QC failure, not a one-off mechanical or material failure.
Were all yours made/purchased around the same time? Were they on different guns, or the same gun over a period of time? Wondering if something in the upper was stressing the gas key if it was on the same gun. Edit: re-read your post and see they were on different guns.
And again, I’m again amazed at the knowledge contained in this community…good to get new information and different perspectives!
And time for me to check all the guns! Microbest or maybe FCD just for the logo, LoL, may be getting a fair sized order soon!