22-250 is an under-rated cartridge. It is one of, if not THE fastest commercial varmint cartridge (204 ruger, 220 swift are right up there) making it have every attribute you want in a varmint cartridge. Long point-blank range makes them great for gophers and coyotes. The down side is it is harder on barrels - lots harder - than a 223. You can definitely make them work with heavy bullets, but for F-Class, this puts you in F-Open, and you simply aren't going to win much with a 223 bullet. The 22-250 is the basis of a few excellent long range cartridges, such as the 6XC, the 6-22-250 and the AI version but until someone decised to sub-classify F-Class by calibers, 223 anything in F-Open will not be a popular choice for competition.