Your data is wrong. I've seen it. A movie called "The Killers" with Lee Marvin. He had a silencer on a Colt revolver (Detective Special, 38 cal). No noise out the cylinder/barrel gap. The sound was just a "puff." Plus, no recoil.
Are you saying I can't believe Hollywood? I'm crushed!
Well, to be fair, I didn’t test a revolver, only semiautomatics.
I hear from Hollywood that the revolver is the assassin’s pistol of choice because it is so quiet.