The 500 AHR will get you about 15 to 20 fps more muzzle velocity for the same chamber pressure, not really significant, and that is all the extra case volume really gives you. The 500 AHR does have a slightly rebated rim (not as severe as the 500 Jeffery does), I have ~ 150 examples to prove it. The rim is basically the same diameter as the 416 Rigby (plus maybe 0.005"), and it is thinner ~0.050". If you are going to have one made do not start with a 416 Rigby bolt, as you will have ejection issues big time!

I cannot agree more with 500Nitro's comments regarding the the so-called feeding problems, they most definitely are due to the gunsmiths skill/knowledge and not the cartridge. I also know there is NO difference between either the 500 Jeffery or the 500 AHR (the 505 Gibbs too) on game.

For whatever it is worth that is what I know.

Scott