500 to 700 yards? although a 220 swift is my favorite varmint cartridge I would shy away from it at those distances. 6MM bullet has a higher BC and therfore you wont have as much wind deflection. If it were a custom 220 with a very fast twist say 7.5 or 8 that could handle heavy bullets I think it would then be the ultimate. I've killed a lot of ground hogs at 500 yards with a 220 but after500 yardsthe numbers are considerably less. Check all the ballistics at www.biggameinfo.com Play with the numbers. 6MM is the hot cartridge for 600 yard matches. There is a reason for that.