35 years on a chicken farm (God, has it been that long?) I can't count, literally can not count the number of raccoons I have killed over the years. Hundreds. Pellet guns have no business being used against anything other than pop cans. Just because it "can" be done, doesn't mean it should be done.
Of ALL the methods out there: .22 short, cci quiet or a cb at the very minimum. To the back of the head, 1/4" up from where the spine meets the skull, from behind when in a live trap, is really about the only "humane" death there is for a raccoon.
Hear about the "drowning method" used often enough, but seeing that's, the stuff of nightmares! And would really rather not have to kill them at all, if only the limp-wristed fruitcakes from the city would quit "ethically live trap and releasing" them on our property. I think the pest control companies do it too...