I was recently wondering about this myself so I like the timing of this thread. I am building a SAM-R/SPR type upper and note that the military uses the M84 on both. I wondered about people's opinions about the PRI gasbuster as far as a comparison to the BCM.
It might be somewhat of an apples and oranges comparison, with the PRI costing a bit more than the BCM and the gas diversion being somewhat situational (supressed weapons). I have shot rifle length and carbine length ARs and never noticed gas blow back (I do wear glasses though). I've never shot an auto AR, SBR, or supressed AR.
Any love for the M84 outside of use on supressed weapons? Any point in using one on a non-supressed rifle length gas system gun? Based upon your reviews the BCM seems like a no-brainer on a carbine, but I was wondering about BCM vs. PRI on a precision AR rig.
If you are building a carbine from the ground up it seems almost dumb not to put a BCM CH on for another $25 bucks or so over a standard CH.
Dom

