3 decades ago, I had a Diana 45 .177 pellet rifle... and used it with German wadcutters to rid the neighborhood of some nasty feral cats. Heart / lung shots at 800-900 fps with wadcutters and they dropped in their tracks. As a kid, I used a Crosman .177 766 American Classic with BB's to shoot hundreds and hundreds of squirrels and birds. Those BB's penetrate DEEP. That being said, as I researched and learned, I grew to appreciate .22 pellets, as you end up with about 20% more stopping power, despite a lower velocity (all things being equal, same model / power plant, .177 vs. .22). Opossums, raccoons, squirrels, skunks, etc. often raid my garbage and I like the additional stopping power. Shot placement, yes, its important, and .177's will work.... but I like the extra wallop of a .22! That's why I sold the .177 years ago, in order to get a .22. Plus, my old, fat fingers handle .22's much easier!!