[Drewbacca]

Your mag springs might still be too stiff. Try loading them to full capacity and letting them sit for a few days before you go shooting next time.

 

[Drewbacca]

Also you might check your grip.

I know someone that uses a grip where he pushes against the slide with the left hand, and used to trip the slide open lever during firing.

Also a possible solution. Your thumb could be too high, and when you fire a round it slips up and hits the slide release lever just enough to catch it. Something similar to this happens when I shoot my buddies PT22. The gun is so small in my hand, that every round I fire causes me to flip the safety on.