I agree, it's probably an ammo issue. Glocks don't need to be broken in and they definitely don't want you polishing any parts.With the reputation Glock has, I wouldn't think any break in would be needed. This makes two videos I've seen where the 42 is having problems or complaints. So far (until I get one and can see for myself) I think they are ammo related.
Sorry, but no such thing as a speed loader for a semi-auto. Maybe you are referring to the magazine loading tool that helps you put bullets in the magazine.I know this isn't the answer to your problem, but did your 42 come with a speed loader? Mine didn't, but according to the manual it should have. And how many mags came with yours?