Not a revolver but here is a rifle test I did a while back with
different ammo to get the fps +/- 10fps and the impact area
of the bullets, as the scope was set, later changed.
The ICC subsonic 40gr LHP was a lot louder than the 29gr bullets.
However there are high speed shorts that are just as loud as the 40 S/S.
As a note, if you do buy the CCI 40gr "Quiet", they generally will not
have enough energy to cycle an automatic rifle.