.22 lr subsonic h/p. and work on your aim. In the ear works.
It won't matter if you lose a few cats tho. They'll make more.
No doubt. A little cat control goes a long way, else your porch will smell like cat p!ss, as will every other good marking area. Not too many things smell worse. Start feeding the cats only at regular times, e.g. morning and evening. They'll figure out the routine and show up when its feeding time. The critters will soon figure out there's not a regular supply of food on the porch and go skulking somewhere else. IT also eliminates the cats and critters in close proximity problem, thus alleviating the need for using anything else besides a .22.