The 500 AHR is an improved 500 Jeffery. The improvement takes the form of:

1.) Rim diameter of 0.590" to 0.600" (still slightly rebated), but allows using Rigby shell holders.
2.) Neck lengthened to 0.500" (Case length 2.900") this represents an ~ 0.150" increase in neck length vs. the Jeffery.

My Bertram cases have a case volume ranging between 158gr and 165 gr of water (once fired and full length resized).

I have load data with Woodleigh bullets if necessary, just send a PM.

Regards,
Scott