Any silencer that lowers muzzle blast noise by 20-30 decibels works well in my opinion. Muzzle blast is by far the loudest part of the gun noise from the shooter's position
Compare a gun and a car. A car has engine, tire, wind and exhaust noise. A gun has muzzle, action, bullet flight and impact noise.
A muffler (silencer) only works on exhaust (muzzle blast) noise. Run a car without a tailpipe and muffler and you will not care how loud the rest of the machinery is. Ditto for the gun. While a semi-auto rifle using supersonic ammo is much noisier than a bolt gun with subsonic ammo, using a silencer on the high powered semi-auto does not make the silencer less effective.
A silencer merely needs to be suitable for the caliber and pressure of the gun/cartridge combo is it used on. I use silencers on 5.56, .308 and 338 ultra mag rifles and think they work very well. The 22lr and whisper chambered firearms are of course much less noisy, but a firearm using supersonic ammo is not subject to the rainbow trajectories that subsonic ones are past 200 yards.
Last edited by RAnb; August 23, 2010 at 11:49 PM.