Thanks for all the suggestions.
I think I'm going to take him to the range again and see what other range guns there are for him to try.
Wheel guns are out due to his arthritis. 1911 had the easiest trigger for him at 2 lbs and he loves the platform, but Ergos aren't good.
Recoil was not a problem for him in 9 mm on any of the platforms he tried.
My plan was to reload some softer ammo for him - he used my reloads at the range during past sessions with no issues when trying mine, and ammo for the range guns was what they supplied - they don't allow home reloads to be used in their rental fleet likely for good reason.
I agree about revolvers. Double action requires a heavy trigger pull & single action requires moving the grip and cocking the hammer.
Both are difficult with a wheel gun.
Since you reload, I would suggest not only some soft loads for less recoil but that way you can go to a lighter
recoil spring & lighten up racking the slide.
Try & go with a second strike option in the event of a misfire. That way he can simply
pull the trigger again rather thank rack the slide for a new round.
Front serrations on the slide might help him also.
Arthritis sucks ( I know ). But there are ways to make shooting easier.