I own a 629-1 and a 29-2. The advice given to me from the gunsmith at the shop where I bought them was shoot nothing heavier then 240 gr as that was the bullet these guns were designed to shoot.

I've tried to follow that advice as I shoot a 250 gr LSWC Keith bullet at 1100 fps. It's easy on the gun and me. Both guns have not seen a magnum load since I bought them.