The messed up screw does not concern me, but the less than solid lockup would concern me. The screw being marred makes no sense as there is no need to remove the ejector rod housing to remove the cylinder for cleaning. I occassionally tighten screws that come loose from shooting, but that never mars the screw heads. In any case, a new screw would not be much of a hassle, so this one is really not a concern. The front sight, while black, on my .22 LR M97 does "shine" a bit in some lighting, so the sight black makes sense.
I have a 5.5" .357 Magnum M97 with fixed sights as well as the .22 LR M97, and they both lock up just about (but not quite) as tight as my M83. The .357 does have a bit of a turn line after several thousand rounds, but the lockup is tight. Something to check after getting burned on my .22 LR M97 used purchase. With the hammer at half cock, check to see that the bolt stays in the "down" position in the frame. It appears the previous owner of my .22 LR M97 tried to give it an action job, and he messed it up, causing the bolt to try to lock up prematurely. I wonder if your turn line and the timing issue are indications of some kitchen table smithing.