If you don't mind fire forming brass, buying custom dies etc. You might consider a cartridge that I just developed which I believe is the best of both worlds .I shot the barrel out of my 6,5-06 AI and decided to build something similar, but with more suds. It is based on the .270W case. It has the 40 degree shoulder of the Ackley and the case capacity of the Gibbs but with a much better neck. It's dubbed the 6.5 Sherman. I rechambered my 700 Rem, with a 26" Lilja barrel. I can safely send 140 bergers down range at 3200 fps without destroying cases although accuracy is better at 3100. A .264 mag uses about 10 more grs, of powder, so my barrel should last longer. I fired a group today at 3100 fps that measured 1/4". Let me know if you are interested in knowing more.Feel free to contact me.....Rich
For those of you who may think I'm overloading, I have fired the same cases 8 times now and the primer pockets are still tight.