Just a suggestion, but a pellet to the head is just as effective on feral cats as it is on a squirrel. Feral cats were what got me to buy my first "adult" airgun, not only do they kill just to be killing (gee, that sounds like another critter on this planet we all know), but they insisted on using my porch and flower beds as litter boxes. And if a not so feral one slips in, oh well, dog owners have to keep their animals under control, the same should be required of cat owner. Later.
Dave