Ha ha , used to do a bit of that while working in Texas a few years ago , but never from horse back and beer cans don't shoot back !!
sod that, I want bigger guns, and fully automatic, I want to take him down, and his horse, and his gran.
don't know much about hand guns tbh and have only fired a few 45's I do know that they are notoriously inaccurate though. have owned alot of riffles though ( not that I know much about them either!) my fav was a 1906 Winchester 22 that my brother bought me for $50 kiwi. Bout 2'6 long it broke in half with 3 turns of a thumb screw and would go in a small ruck sack. 2nd fav and so accurate was my ruger 10/22 best 22 riffle ever
.22 magnum..? Only just. .22 or WMR are alright for rabbits or foxes if you're standing on top of them but for cutting your man in half in a duel and making his horse sit down you need a fast-feeding cartridge like 9mm para, .45 ACP or 4.6x30 mm in a rapid fire short-range assault weapon with a rate of fire of around 1000 rounds per minute. Something like an Uzi Micro, or a Heckler and Koch UMP-9 or MP7A1 (a favourite with trigger happy armed police forces the world over). German, Israeli or American, see. Trust the experts. They know how to kill people.
I've bagged rabbits at 80-90 mtrs with a 22. But you are right you need something a lil " gruntier" to cut someone in half! I do know a guy that killed another with a 22 but it was very close and took 9 shots. tbh I think he was fucked after 2 but he put another 7 in his back to make sure. 1000 rpm is spray and pray shit!