Cats and projectile weapons are the only thing that work against rats for me.

There are poisons like warfarin that they will eat and will kill them via internal bleeding, but they will crawl into the most inaccessible part of where you live to die, and make you wish you'd never poisoned him.

They're too smart to step into a baited rat-trap, and there's no way to "repel" them. Anything that will "repel" a rat will repel you even worse.

If they're out in the open, a .22 CB-cap or Short will take care of them without distressing the neighbors, or one of these magnum airguns you guys mention. If they only come out at night, your only solution is a cat. We've had quite a few cats and they're great varmint killers, not asking for much in return.

All in all, we've taken care of our rat problem where I live ... !

Lannis