Sometimes the Germans sniped with 22's during WW2.
I say that because my father served with 3rd Army, and had personal experience with SS snipers using 22's. He got a 22 LR Erma military training rifle from a pair of German SS snipers in Paris and sent it home. My father was in an Ordnance unit, and as he told it, one day he was towing a broken down 1/2 track back to their repair site. They were flagged down by some MP's who said they were taking sniper fire, and one had thought he saw a brick move in a wall in a blind alley. The Ordnance units traveled with everything that would fire loaded, and his 1/2 track mounted a quad 50. My father said he got on the 4X50 and opened up on the wall, then the MP's assaulted the building. The Germans didn't survive the quad 50. The MP's gave the rifle to my father, he sent it home.
The rifle is in my gun safe; extremely accurate, and extremely quiet with standard velocity 22's. I'd expect it would be very effective.
Shotgun