I am a big advocate of the .220 Swift. I love this cartridge. My Ruger Target rifle shoots 1/8 MOA and 100 yards off sand bags with factory Hornady V-Max's and I have shrunk the groups a little with alot of tedious handloading. The .22-250 is another great choice. These are serious long range varmint cartridges. My Swift drops coyotes at 400 yards with authority. The .223 is a good round, but for long distance the large centerfires take alot of the guess work out of trajectory. I haven't shot a .223 WSSM, and I have no need for one (the other two are just as good and easdier to find rounds for). If you are into reloading, the .243 Win is a good choice, it will launch heavier bullets around .22-250 velocities. [/img]