I’ve got a suppressed Ruger 10/22 (22LR) that’s about as noisy as a stapler.

Depends. As long as the bullet doesn’t break the sound barrier, a gun can be made reasonably silent with a good suppressor, to the point where the sound of the semi-automatic mechanism operating is louder than the gunshot itself. If the bullet is supersonic, then it will still be painfully loud.

Sexy mall cop