I have a late 50s Model 37, as well. It stays loaded with Speer 135gr. +P Gold Dots. I don't shoot many of them, so I'm not worried about wear on the gun. If I were worried about +Ps, I'd probably go with the Nyclads mentioned above, or would load a "combat wadcutter" handload and run it about 800 fps. Too bad the Safe Stop standard pressure load is no longer made.