Is it possible to "sandpaper" fingerprints off a surface?
Geraint - Yes, I would guess you could. If you were ablate enough of that surface then you'll remove any kind of interaction. The other advice, of course, is to wear gloves when loading your shells.
Chris - So basically, if you did actually scrape hard, you could erode the surface and then you wouldn’t stand any chance of getting a fingerprint from that.
Geraint - That is correct, yes.