Personally, I have built many 6.5 caliber rifles in all barrel lengths, and to me the 6.5x55 rules the roost. Lapua brass is less than $70.00 for 100, low recoil, and easy on barrels. If you want speed try IMR 4831, 46.4 grns., 140 VLD and CCI primer, my chrony shows 2911 fps out of a 24"...