The problem with silencing a revolver is the gap between the cylinder and barrel. Unless in the case of the above mentioned exceptions which seal the barrel to the cylinder in the fire sequence, there is enough “BLOW BY” of high pressure gas that leaks out of this gap to make a considerable noise. Since this gas excaped faster than the speed of sound in most cases, it makes a sonic boom by itself. The rest of the gas fills the chambers of the silencer then escapes after or as the bullet leaves the silencer. The silencer will reduce noise for a revolver somewhat for it does absorb a lot of the high pressure gas then releases it under lower pressure, but not as well as, say, if used in a closed system such as a semi auto hand gun or rifle.
Most revolver cartriges don’t push the bullet faster than the speed of sound (1100 ft/sec approx.) in the first place so there is not sonic boom as the bullet exits the silencer, however, .22 jet SW, .357mag from a six inch barrel or more, (snub barrels most often don’t permit enough time for the powder to burn fully resulting in a much lower muzzle vel), some 44mag and .41 will exceed the speed of sound if using factory ammo. If you reload then you can buff down the charge to something under the speed of sound. But all in all, silencers don’t work well attached to a revolver. Also, revolvers have a front sight which doesn’t permit threading of the muzzle unless a gunsmith moves the sight back about an inch to permit barrel threading. Some barrels are not round, they have a sight ramp or rib and that must be machined off to permit threading. Bottom line, select a semi auto to silence if you want a silenced hand gun.
A bit off subject, I find that an ordinary .22LR semi auto is an excellent gun to silence. Often they have a 10 rd mag that gives you all the protection you need in most cases with fairly well placed shots for personal defense. Head (brain case), heart. They stay on target with little recoil and you can pump several shots into the target to ensure effective trauma. A heart shot won’t instantly drop the assailant. In actual combat I’ve seen targets run, walk and “live” at least fifteen seconds with a heart wound. In those fifteen seconds they can shoot back or knife you fatally if close enough. A brain shot however or eye shot will drop them in their tracks due to concussion effect in the brain itself. A shot to the base of the skull will trim the spinal cord and down they go instantly with no messages from brain to body’s nerves. The cerebellum at the base of the brain when trimmed by a shot will drop the assailant instantly as well. A neck shot that trims the spinal cord will also. The last targets metioned however are more difficult to hit if the target is moving, running, dodging etc. and a volley of say half dozen fairly well aimed shots may hit the vital zone (and may not). A gun fight is always risky and doesn’t follow Hollywood’s portrayal at all. If the target is high on certain drugs, bullet trauma often has less immediate effect as well due to pain dulling and other sensory dulling which permits the target to keep engaging when a target not under the influence of the drugs and sometimes alcohol, will feel the effect of the trauma more. Certain drugs augment a will to succeed or augment the ego to press forward such as crack, cocaine and meth which helps in many cases the target to keep on coming even though you hit fairly well into the thorax or abdomen.