Yeah, BCM seems to get it right.............I have one of their uppers with mid-gas, non-adjustable GB & it shoots & handles everything from low pressure 223 - full blown mil-5.56 absolutely 100%. Even steel case junk.
Ditto for a Sig factory upper & most recently, a PSA 14.5" mid-gas gun as well................just perfect.
On all my builds, mainly just to make life easy, given the mix of parts, etc, I've just decided to use an adjustable GB even at the added cost. The cheaper ones from Seekins or ODIN are not quite as nice as SLR's but they work just fine, IMO. The key is to actually adjust them from time to time & even clean them too, (God forbid).
MM
