We lived dead-center in the city until almost 3 years ago and were keeping pigeons for dog-training. No one bothered to clue us in that keeping pigeons results in keeping rats.... I got to be very very good at killing rats with my GAMO. Put the varmint pack on it (light & laser) and would lay prone in our driveway for hours picking off rats as they investigated my peanut butter bait pile. Also killed a possum with it - it was predating. At first I was all, "Oh cool, a possum! Wild Kingdom in my front yard!" but that feeling passed as soon as I saw her climb the flight pen, reach in and grab a sleeping (stupid) pigeon. Damn things were costing me $5 each, no possum gets them!
Hyper-reactive neighbors had no idea. Less of a "crack" then hammering a picture hanger into the wall. And mine is not the "whisper" version, either. It didn't like those PBR pellets that GAMO pimps - much much lower accuracy. Regular pellets and I could shoot the eyeball of a nervous biggie norway rat from 15 yards. I don't think *I* would want to go much bigger than the possum, but I know that some take feral hogs with pellet rifles.