Will be shooting at 600, 800 and 1000 and was looking at 308 or 30-06 help me decide as I have a chance to purchase a m40a1 type rifle in 308 or let it pass and have 30-06 built. Would probably use 175'smk barrel on m40 is 11.25 twist at 24. Would do you think. I am learning how to reload through a friend so ammo would not be a problem. Thanks a bunch