I tried out my KKM 9mm barrel in my Glock 23 the other day, factory Glock 9mm mags too. I had serious extraction problems, about every 4th round failed to come out. The next fresh round was jammed trying to get inserted into the chamber with the empty still there. This was the same over the course of several magazines. These same loads work fine in my 2 other 9mms. I just got back and have not looked anything over yet. Before I go further, or just stick with the 40 cal, is there an easy fix? Would an extractor change help & is it something a mid-grade shade tree gunsmith can handle? If this is how it is I'll cut my losses & stick with the 40, if it just takes a minor alteration I may continue. I was at least wanting higher reliability for woods carry if able. I do realize the 40 itself is fine. When I did switch back to the 40 reliability was back to great.