Hello All, I got a Grand Power P40 10mm a few months back and was having issues feeding the last round in the magazines. I believe I just figured out the problem and wanted to share for anyone else having the same issue.

Sorry but I forgot who suggested it but I polished the breech face and then the extractor which I believe was the real issue.  The exactor had some sharp edges that was digging into the brass as it was sliding up the breech. At home while cycling it I took a sharpie and marked the brass on a misfeed round then inspected it and found a big gouge on the neck of the brass where the extractor was making contact.

I did have to do a little filing to get the sharp edge off then polished it with a Dremel  with polishing compound. 

Before it seemed to misfeed every 3rd magazine or so, today I just ran 50 magazines through it with no issues whatsoever   . Happy Camper!