In the Charles Portis novel Cogburn shoots the right two times without aiming using Mattie Ross's Dragoon revolver. In the 1969 John Wayne version Cogburn uses his own SAA to shoot the rat. In the Bridges version there ain't no rat shooting at all. And no cat named General Sterling Price either.
You can't serve papers on a rat Baby Sister, you gotta shoot him or let him be.
"A Liberal is someone who doesn't care what you do, as long as it's mandatory". - Charles Krauthammer