I’ve bought somewhere north of 400 BCG’s (I THINK still south of 600, but maybe more) in the last 20yrs, with most of them from Bushmaster, DPMS, Rock River, Toolcraft, Aero, Rubber City, Brownells/Azimuth, JP, BCM, not sure who I’m forgetting…
I’ve bought even more barrels than carrier groups; a lot of Shilen and Krieger, Black Hole Weaponry, Tactical Ordnance, Proof Research, Craddock/Bartlein, and a bunch of cheaper Faxon, Odin, Hanson, PSA, Daniel Defense, Ballistic Advantage/Aero, Bushmaster, etc barrels along the way…
Out of all of those different combinations, I have checked headspace on ALMOST all of them, and I can’t recall any which didn’t combine to create appropriate headspace which were because of an out of spec bolt. I’ve seen some sloppy chambers, and I have been shipped BCG’s which had the wrong bolts installed for example, I’ve received x39 carrier groups which had .383” bolt faces - 5.56 bolts - and I received two .458socom carrier groups which had .435” boltfaces (6.8spc) instead of .487”, which were simple inventory mistakes upon assembly. No harm, no foul, the sellers replaced them promptly.
Improper headspacing is a specification control issue, not a brand quality issue, as every brand can have mistakes slip through the cracks, or have a product right on the edge of defect which “passes” one test in house, bt then is found to “fail” when it is released into the wild and the test is done with a different device. Bad barrels and bad bolts can and do make it out to customers, from every brand. Online claims that one brand or another are LIKELY, or even MORE LIKELY than others to have issues are almost always BS brand bashing by inexperienced liars who simply want to sound like they know something to online people they’ve never met… and equally, I’ve never heard of any company not standing behind their product when a customer finds a bolt or barrel chamber to be out of spec (again, other than brand bashing liars online). AR’s are pretty hard to screw up.
I think this thread is chasing a bad idea, in general. Anecdotal, singular reports or brand bashing without even the reality of the singular experiences aren’t worthwhile in the vast universe of possible parts combinations.