The narrow shoulders of the standard Whelen case cause issues with headspace in the original and the improved versions give you positive headspacing and extended case life.
IIRC the standard AI has a 35 degree shoulder and the Brown Whelen 40.
Headspace problems with the standard .35 Whelen? News to me. Folks make the .400 Whelen work without a hitch.
ACKLEY Improved cartridges are all 40 Deg. And I'm talking the ones P.O. designed himself, not others that folks just call AI.
