For fun, I highly recommend that you take the .500 Mag stoked with one round of 500gr Hornady XTP-FP in your strong hand, and in your off hand, take the .460 with one round of Hornady 240gr XTP-Mag and single action cock each one, then simultaneously allow them dogs to BARK!
Why do I recommend these bullet loads specifically?
Well, simply, because that's what I happened to have on board when I did it. Twice.
Both revolvers have the 8 3/8" barrels. I highly recommend that you pick aiming points a few degrees off of each other, not pointing in the same exact direction. Obviously, you need a proper place to pull off this exercise. That aiming tip is so you don't accidentally ding the muzzle ends together in full joyous recoil.
It's a very fun and very different experience and much like shooting either the .460 Mag or the .500 Mag, it's not nearly as bad as one might imagine it to be. These guns have been designed very well to handle the recoil of these cartridges.
Man the percussion from both going off at the same time might jar all my fillings loose
That can be an expensive range trip.