When I look at the equipment list for the bigger matches I rarely see short barrels on there. Pick a 26-28" varmint contour barrel in the caliber of your choice and rock it. The 260 will work fine as will 6.5 creedmoor or 6.5x47 Lapua. I would probably go creedmoor just because the brass seems to be a lot easier to find and not very expensive.