To the review that gave it 2 stars cause it wouldn't cycle subsonic ammunition - Faxon Firearms 300 Gunner Rifle Barrel

Ok if you don't know anything about .300 blackout maybe you shouldn't even be building one until you do some research . . First off , the gas port most likely isn't too small. You will rarely find a 300 bo that will reliable cycle subsonic ammunition WITHOUT a suppressor or at least a good krink style break to create back pressure as the gas port size is tuned to run supers and run subsonic with a suppressor . Next if you don't have a suppressor, you don't need an adjustable gas block on .300 bo. Probably still wouldn't need an adjustable gas block even with a suppressor cause the barrels gas port is tuned to the correct size for optimal performance. Can't see someone writing a bad review over their own lack of knowledge.