bogardus6686

I ran into the same issue on an old 550 i have, I discovered it was the powder drop catching tho top of the case occasionally and making a spot just like in your pic. I never did find the root cause other than the case wouldn't line up perfect sometimes. Check to make sure everything is tight is the best advice I can give. My press was 25+ years old, so I know I had a few loose spots.

The hole the pin is in is much longer than necessary for the pin that's in it. The only reason is so you can drive it out. As long as you don't cut so far you hit the pin you should be fine.