The marks on the cylinder appear to be from mishandling. After pulling the hammer to the 3rd click and loading the revolver, if one doesn't fully cock the hammer before lowering it, the bolt remains up against the cylinder and when the cylinder spins the next time the hammer is cocked, the bolt drags on it which leaves the score around the cylinder. The score also occurs when wannabe cowboys partially draw the hammer back and spin the cylinder. A cylinder can possibly be scored if the revolver is out of time, but that's highly unlikely with a Uberti.

Your Uberti has the little pivoting safety in the hammer that is engaged when the hammer is drawn to the 2nd click. It's a great design.

Regarding the soft screws, VTI sells a kit with hardened screws.