I recently took my G20 G3/SF apart and did the 25C trigger job. I.e. polished all the trigger metal parts. The first couple of times dry-firing it the pull feels much better, (smoother). But if I keep on dry-firing the pull requires more and more force until it gets almost impossible to pull the trigger. It's still smoother than it was before the polishing. If I take the frame apart and re-assemble again the pull goes back to being normal again but degrades to require more and more force. (I meant to post this to Glock talk. But I can't sign up - the admin has banned my IP and doesn't respond to PMs...) Any 2 cents welcome!