If you're tuning your AR for suppressed operation, you'll likely change to a suppressor specific gas block and change the buffer. Most suppressors will come with a mount that's either a muzzle brake or flash hider. Larger calibers come in direct thread but most AR (5.56mm) will have QD mounts. When you shoot unsuppressed (why, in God's name would you ever do that if you can have a suppressor?) the operation of the firearm will obviously be different. You can't have a one size fits all because of the back pressure and gas difference between configurations.
Check out YHM.net for specifications for models like the Turbo T3, Turbo TK, Fat Cat and Cat's Ass (everybody wants one.) Looking at larger calibers like the Bad Larry (338), Resonators R9 and R45 will give you a good overview of mounting options.
YHM also has an excellent gas block specifically for suppressed operation.
