Well for those that have read some of my post, you will see that my to favorites are the 26 and 30 calibers for two reasons bullet selection with high bcs and accuracy. I will break it down for you like this. Consider the of a long action for all of this info. The greatest to least powerful 26 calibers 6.5x300wby, 6.5stw, 6.5x300wsm, 264wby, 264wm, (6.5x284, 6.5remmag, 6.5-06AI, and 6.5gibbs are so **** close I call them a tie), 6.5-06 non AI, 6.5x55swede, 260AI, 260rem, 6.5x47lapua, 6.5tcu. You just reverse that list for longest barrel life for rapid firing. The most accurate is kinda tied to about 500 yards (6.5x284, 6.5x47, 6.5x55, 6.5-06AI, 6.5-06, 260AI) then it starts to fall off with the 260rem and all the high power and wildcatted mags. If you want to use a 6.5x47 at 1k I suggest you neck it down to a 6x47 and use 115 bergers in a 26" or longer 1/7 twist barrel cause the 6.5x47 doesn't have a big enough set! The 6.5x284 would be my first choice, second would be the 6.5rem mag, and third would be 6.5-06AI. Just some of my experience and opinion good luck with your build.