I have used an R9 on a G19, 9mm PCC, .223, and .308 Win. It is a very quiet can with subsonic 9mm. You can get multiple attachments (pistol booster, direct thread, QD, etc) and so far they all have worked well. It actually suppresses the 223 and 308 (16” barrels) better than I expected. As was mentioned, it is a bit bigger in diameter, so taller sights (or a red dot) are necessary on a pistol.