[Alleycat]

A lot of actions have problems with the abbreviated 300 WTF case. I would go with what Spook and others have suggested. As far as a 9mm suppressor, I can't give you a good answer. If someone with Quickload wants to run the numbers for you it would give you some idea. It's basically muzzle presser that you're after. If supersonic 300 out of a 16" barrel has the same or lower muzzle presser as a 9mm out of a 4"ish barrel it will be safe. It will void all of the warranty's but it will be safe. Depending on the suppressor that you're looking at, It may run you around what a 30 cal can would cost. A Tirant or an Osprey would be bad ass on a subsonic 300 or 338 Specter SBR. Very few of the suppressor manufacturers will tell you that you can use their 9mm suppressor with 300 Whisper supersonic ammo. The ones that do will probably violate your weight restriction.