I know you said you don't reload but just be careful playing with subsonic 308. Powder is designed to burn at a controled rate and if you follow some of the insanity I have seen posted on the web you can experience an instant ignition of the powder charge and KABOOM your gun!
Consider buying a 300 Whisper or one of the other .308 rounds designed to be used at subsonic speeds. I have a YHM 7.62 Phantom and I use it with supersonic 308 ammo but I also use it with both supersonic and subsonic 300 Whisper loads. The subsonic 300 Whisper have virtually no blast to contain so you end up with a gun that is quieter them most supressed 22lrs to put it in perspective and that is with a 240gr bullet!
Anyways, just be real careful if you get some fool to send you directions on how to roll your own! Some of the advise I have seen shared is enough to give me the warm fuzzies!