FWIW, I already decided to go with an AR style SBR in 300BLK for this single purpose weapon. That's why I framed my original question as I did. All I was really looking for was advise on setting up such a rifle with regard to the gas system to "tune" it for the best balance of recoil, muzzle jump, ejection site gas, and cycling reliability. Within that framework, I do appreciate the advice on the supers vs subs, because it does impact the noise and would impact the gas system. It's hilarious how guaranteed it is to start with such a non assuming thread and it ends up in a death match. That's the way of the Campfire though
