Here's the parameters. I have an Accuracy International AI AT. These for those who don't know these are short action switch barrel rigs with a .473 (308) bolt face so no WSM's, they run a magazine that is slightly more generous than some other short action mags. If my measurements are correct it looks like 2.950 OAL is the max I can get in the mag. If I were going to get a barrel spun up and my goal was to deliver the highest BC bullet down range with the highest velocity possible with the overall plan being to extend my terminal range by having the highest amount of energy on target at distance within the given parameters what cartridge would you all recommend. I'm guessing 6.5 or 7mm is going to be the way to go in order to balance high B.C. bullets with maximum velocity. The 260 Ackley Improved is the best I can come up with. Is there any others out there that I'm over looking?