The .22 Shotshells have ever only been used for snakes in my life. It's very satisfying to watch those fuggin snakes squirm as they die.
The .38 special shotshells are pretty much the same thing, but about 10 feet more range.
There are a few ways to deal with your raccoon. One would be to poison the food.
Another would to be trap the raccoon, and then drop the cage with a barbell into the pond.
The last option would be to just beat the raccoon on the head with a blunt object. Especially if it's gotten complacent.
The .22 will not kill it, unless you get it to sit still, and I've never seen a raccoon sit still.