john2a said:What about a .243 win? Lot's of choices on ammo & good data?
John Whidden uses a 243 Win in long range prone competition and does very well with it, but I don't know any top level F-Class competitor using a 6mm in regional or national level competition. Some 6.5s do very well, but most are now using some flavor of 7mm and there are some big 30s from time to time including a 300WSM that won the 2010 FCNC. If you already have a 243 Win and want to try it, go ahead and see if you like F-Class, but if you are building a gun or rebarreling, a 6.5 or 7mm would probably be a better choice.