My Gen3 G27 does not have the polymer gouging as shown in your pictures. It has the crescent-shaped area of missing polymer that I would assume is a molding void, but it does not have any of the other gouging/scraping marks shown in your pictures. My G27 has the original factory RSA and I've put 100 rounds through a spare RSA, both are factory with the solid black inner metal sleeve that holds the larger outer spring, they are not the newer version that has the silver sleeve with 0-8 or 0-8-1 on the metal base of the guide rod.
It's possible that the silver metal disc on the guide rod that fits into the crescent-shaped notch on the barrel lug is sharp on the edge and that's what's causing the gouging/scraping to your frame. If it were happening with my gun I would take a 1000 grit ceramic knife sharpening rod to the base of the guide rod to smooth and round off any sharp edges, then see if the gouging/scraping continues.
You might even try an aftermarket RSA. Enough people have had problems with the new 0-8 and 0-8-1 RSA's that when I use up both of my early factory RSA's I'm going to get an aftermarket replacement. I haven't heard a bad review of any aftermarket RSA for a G27 but I'll likely go with one from Wolff Gunsprings or a stainless one from LoneWolf or Glockstore.com.