I had a problem with a family of feral cats that was taking up residence under my pier and beam house. Noisy, and when the toms came in to mate, could get smelly, too! (And noisier still.) I blocked off the underside of the foundation, but this was an old house with a busted footing, and they kept getting around me. I was renting, so I wasn't going to put all the work and money into repairing the footing. The cats had ribs showing, and would run like crazy whenever I came into the back yard where they were. They were a pair of adult cats and 5 adolescent cats. When I saw that one of the adolescents was pregnant, I took action. I opened my back window of my bedroom and placed pillows around the window, and put an open can of tuna in front of an old oak tree in the back yard, about 20 feet out the back door. The angle was high enough that even without the tree, the bullet would have gone down into the dirt. I got a couple of chairs and set my Remington bolt action .22 rimfire so that I had a perfect rest 8 feet inside the room to shoot the can of tuna. I then made lunch. I came back into the bedroom, looked out the window, and saw the cats coming to the tuna. I loaded a CB cap, held an inch over the head to offset for the scope at short range, and squeezed. One very compassionate euthenasia. Without even retrieving that expired cat, I was able to do it again. I then disposed of the remains, and did it again. Over a weekend, I removed the problem, and felt better for it.
All of this took place in the middle of a city limits. No one ever knew, although there were houses and apartments all around and a busy street just 60 feet away. The house absorbed the sound, and the tiny clap of the CB cap was pretty easy to attenuate, anyway.