I know this is a controversial topic but I have a rat problem in my garden. I see no point in shooting the bastards with a thing that they can head off or crawl away and die in agony from.
You've sort of answered your own question there --- use a rifle, they have more power and they're easier to place a pellet correctly with for humane dispatch.
This is why the Admin team don't condone the use of pistols against live quarry.