Your indexing roller is the newer metal style and shouldn't be an issue unless the roller bearing is actually seized or the arm is bent? The older ones were plastic rollers and easily damaged during mag changes.
I had indexing issues with my 1st L2, a used .22 250mm. The cause was the barrel not being seated all the way forward and 2 of my 4 retention plates being warped. While dealing with the issue, I gouged the hell out of both of my red aluminum mags like you did. That is caused by attempting to fold the stock after the mag has failed to index completely to the next round. I learned to manually index the mag (rotate by hand) before opening the action. I gently filed the burrs from the edges of the gouges and was able to use them again once everything else was sorted.
Regarding the .30 mags, my used .30 came with slug mags and they work great.... with slugs. They are a bitch to use with pellets! Takes a lot of force to get the pellets skirts seated all the way, causing the retention plates to not be completely seated on magazine.... resulting in a nightmare of indexing problems. I lucked out and was able to snag a couple of standard pellet mags from the classifieds and they are much more user friendly.
Hope this rambling helps!
