I have fixed pistons that have crunched a ring land from a foreign object (head of a carb butterfly screw) getting between the head and piston and pinching the ring. Fixed with a small file. Car never changed et ...even before catching the problem.
A butted ring ,even slightly, will score the bore badly. What does the bore look like?
B 1 the bores looked ok except for scratches from another issue. I figure the butting was very light, like maybe .001 too tight at some point when the motor was lean or warmer than normal.
