To install one that times/indexes (as looking at the front of the gas cylinder) finger tight at 5:30 and to be tightened to 6:00 with a gas lock wrench, for the purpose of the gas cylinder not moving around and proper functioning.why would you replace the gas lock?
The schuster plug is for running hotter loads. If you are a do-it-yourselfer read up on gas system shimming, unitizing, and piston grooves. I don't know why anyone would replace the gas lock, maybe fitment when it was shimmed.Ive read a lot about people replacing the fore end of their M1A, but aside from replacing the gas plug with a Schuster upgrade to reduce the op rod slamming....why would you replace the gas lock?
I use IMR 4064 and 175 gr SMK in my reloads and it won't hurt the rifle. Now anything slower then IMR4064 and heavier then 175 grains well your on your own there...I've used several SEI gas cylinders and pistons. Very high quality and easy to clean.
I use a Schuster overbored and vented (non-adjustable) on all rifles. Federal GMM 175gr has 43 grains of 4064 in it, which I consider to be a hot load.