Circular. Kinda conical.
What shape are the springs in?
Make sure that you are fully racking the slide. Pull it all the way back and then let it go into battery on it's own. Also make sure that you aren't overloading the mags. A lot of Glock mags I've had will do this if they have one round too many in them.
If if keeps happening, take it to a Glock armorer or send it into Glock...
The issue is with it sticking before it is fully racked
The issue is with it sticking before it is fully racked
Is the slide being held up by a round being chambered or the slide catch? Hmmm
Try a different mag
Didn't think it would help but it was the easiest and most obvious choice to start with.