I've found that a .22 shooting CB shorts is very, very, quiet - actually quieter than most air guns. I've used them to dispatch marauding squirrels in my backyard garden for years. They shoot a 29 gr. bullet about 700 fps, and the sound is a mere "pfft." The bullet is heavier than a pellet and IMHO is more lethal. Consider it, since if you already have a .22 you can save yourself the bucks you'd spend on the air gun.