Pretty much use the reloading data from the .475 L for the the .500JRH.
Case size is VERY close. Recoil is load dependent.
Average factory .475 load, 400 grains at 1350 fps, and I get all of that and a bag of chips out of that custom barrel. Recoil Energy of 37 foot pounds, and Recoil Velocity of 27 fps. This load is easy if you are used to it.
My range master wanted to fire it. Like about 3 other experienced pistolsmiths he shot ONE round. He used the John Linebaugh technique and the hammer came about a 1/2" from going into his ear, on the far side from where the gun started. These loads are near double medium .44 magnum loads.
I have a LOT of 440 grains at 950 fps for the .500JRH:
Recoil Energy of 22 foot pounds, and Recoil Velocity of 21 fps. Recoils like a mild .44 magnum, hits like a Ford truck, and penetrates like a gopher on speed.
Heavy JRH is 430 grains at 1350 fps:
Recoil Energy of 42 foot pounds, and Recoil Velocity of 29 fps.
Hunting guys swear this kills like a 375 H&H.
Handloads for the .475 are minimum pressure loads of AA 9. 275 grain Speer HP's at 1560 fps:
Recoil Energy of 26 foot pounds, and Recoil Velocity of 23 fps. This is my deer/varmit round. Tends to mess up a lot of meat, and leave a 4" impact hole. It's also my under the pillow load. Figure it wouldn't take many to convince anything/anyone to go the other way.
The FA 83 grip design, coupled with Jack Huntingtons' custom oversized grips for my large hands make these guns the easiest shooting big guns I've ever had. Better then my Seville in heavy .45 Colt with heavy loads.
I also find the grip for my hands is better then the Bisley on my Maximum.
For a warm up you just shoot the 525's at 1350 fps with the Bisley grip:Recoil Energy of 54 foot pounds, and Recoil Velocity of 31 fps.
If your hand isn't split in two, the .500JRH and the .475L feel like .38's.