I have perfected this method with Rabbits, but haven't had much luck with rats. The hammer to the skull doesn't require much force and instantly kills them too, there's no pain. Yeah the carpet is nasty because of the blood. I didn't know a screwdriver would work to hold them down, I will try that if I ever have to do it again. Either way I make sure they aren't in pain, but this way would definitely be much cleaner.