Green’s Dictionary of Slang

(US, Western) a top cowhand.

1938		B. Conlon ‘Rope Meat’ in Wild West Weekly 22 Oct. 🌐 Clay Barton didn’t like the looks of the ranny.
1948		W. O’Sullivan ‘Killer’s Cue’ in Range Riders Western Jan. 🌐 I’d say these rannies who are stickin’ us up are the road-agent gang.
1959		N. Nye Long Run (1983) 155: Irish, shake hands with this ranny. New boss out at Star Cross.
1961		L. McMurtry Horseman, Pass By (1997) 106: ‘See you rannies,’ he said. ‘Don’t get sores on your butts.’.