I just got 4 Mec-Gar 10 round magazines for my SP-01. Load 'em up and insert with the slide back, slapped the mag in and it dropped the slide. Stock magazines don't do this. Insert the Mec-Gar gently and the slide stays back.
Disclaimer: I'm new to this pistol and haven't got everything figured out yet.
Any guesses as to what is going on?