Jeffery versus Schuler and the genesis of the .500 AHR.
I have found that the .500 AHR shoulder angle is nominally 25° which leads to an interesting comparison with the .500 Jeffery/12.7x70 Schuler.
http://www.cartridgecollector.net/500-jeffery

Compared to the Shuler version it looks like the .500 AHR is closer in case and shoulder dimensions to the 1928 Kynamco print of the .500 Jeffery, with the significant alterations being only an increased rim diameter (.590-.600” of the .416 Rigby) and an increase in overall case length to 2.9” in order to achieve a .5” case neck.

It would be an interesting exercise to see if the modern Kynoch .500 Jeffery as well as the CIP Spec 12.7x70 Schuler would or would not safely chamber in the .500 AHR. Of course extraction would be another issue........
- Mike