When a .264 bullet diameter is needed, I always tell guys to try the 129 gr. Hornady SP #2620. My Kimber-sporterized Mod. 96 Mauser loves 'em in conjunction with IMR-4831 and I'm always hearing good things about that bullet from others. A while back I was talking to the owner of Ruger M77 in 6.5x55 and his pet load also involved that bullet, but I forgot what powder he was using.