Just remember that a Revolver has a Barrel Cylinder Gap where the gas escapes and so what would normally sound like a pellet gun out of a .22 Rifle is still a bit loud indoors from a Revolver. Most semi autos won't cycle with lighter loads but can be fired single shot.

I actually find that out of a Rifle .22 shorts are quieter than CB Longs are. CCI's Quite .22's are also pretty good and they are still 40 grains! Again, from a Revolver it's hard to get anything truly quiet to the point you will not need ear protection indoors.

PS: I have a tin of the Acorn loads and a tin of Floberts that I inherited - but never fired.