All,
An update to my problem—the gunsmith found and removed some unwanted end shake, and also fitted an oversized cylinder stop by Power Custom that he sourced from Brownells.
I loaded up ammo and range gear in the car then drove 45 minutes to pick it up (total cost $115) then another 30 minutes or so to the range. The weather was perfect, and I was the ONLY person at the outdoor shooting range (which has about 75-80 firing points), so I was quite pleased....
....until I reached into my range bag and pulled out box after box of .357 Magnum ammo—with not a single .357 Magnum revolver in sight!
Fortunately I had my Colt Delta Elite 10mm Auto with me, which I hadn’t fired in 15 years or more. So I had a grand time with that. But I will have to wait until next week to find out if my Model 29 is well and truly fixed. Next time I will ONLY be shooting .44 Mag and will double-check to be sure I bring the right ammo with me! Duh!