My guns:
- K-22 revolver 4 inch
- Ruger 10-22 rifle 18 inch
Ammo:
- Aguila sub-sonic (22short case, 60 gr long lead bullet, really light powder)
- Federal, Winchester, Aguila and other standard velocity 22LR
- Aguila Hyper-sonic (1700 fps) 22LR
In every combination of the above ammo in either gun, the revolver is louder than the rifle. That includes comparing the subsonics in the revolver to the standard or hypers in the rifle.
Not really part of your question but...
The subsonics don't feed worth a darn in the autoloader 10-22 rifle. Not enough recoil to work the action. The huge, lead bullet in the subsonics fouls up the cylinders of the revolver pretty quickly (just a few rounds) and makes case extraction difficult. The subsonics aren't very accurate in either gun. At such a low velocity, I think bugs jump on the bullet in flight and hitch a ride.
Short answer, sub-sonics don't make very good hush puppys, at least not in a revolver.
Sgt Lumpy