Had an interesting one today at the club. New guy bought a G43 and had the dealer put a red dot on it.

He loads up a magazine and shots, rounds won't extract. Slide comes back and empty is still in the chamber.

I took is apart and found that the the extractor pin was not touching the extractor.

Turns out this has happened before to this dealer. He told the guy to remove the red dot.
Apparently the screw is too long and the hole in the top of the slide goes all the way through to the extractor spring/pin channel.

new one on me.