PLUS ONE to Cliff .......
When I did this stuff for a living, I lost count of the number of Lever Side Springs I wound up having to replace. There were some I actually twisted a Magna Tip like a piece of Pasta and the screw didn't budge (Push it out of the frame). Some had to be drilled out. Horror stories. Bongo (Uberti's pet Gorilla) can really tighten screws.
This has created a little niche market for Hardened screw sets. Kicker is, once the screws have been removed WITHOUT being buggered up, they (OEM screws) are just fine. Rule # 1. Never ever torque dry threads. Bad JUJU there. Hardened screws aren't a bad idea for screws that are removed/loosened frequently.
Something I forgot to mention (oops). Once the lever side springs are out, if not being replaced (bad choice) outright, the rear of the spring boss MUST be shaped (file) to fit the radius at the frame or the spring will just set catiwumpus again and will NOT seat properly in the frame.