I don't know why I keep drawing cowboys (or in this case, cowgirls), I don't even particularly like westerns. There's just something about the cowboy aesthetic that appeals to me. I think it's the revolver. I'm not a big fan of guns, but the revolver is one sexy piece of machinery. Modern guns hide their moving parts, while the revolver shows off its elegant mechanisms.
I think this might be the same character as the girl in this piece, but I can't be sure.