Suppressors work on all calibers, but the smaller the caliber, the easier it is to suppress the sound. 22's being the most common. The sound you hear on TV is just a canned noise, as real suppressors will sound differently depending on the caliber, ammo, can maker, medium (if any), etc.... The noise made from a single clip of ammo through the same suppressor can change pretty easily depending on whether the medium inside the can is wet or dry. Wet medium usually drys quickly, so the 1st shot through will sound more quite than those after it
The few I've shot (22lr & 9mm) worked quite well