Good luck at the range. Hopefully your problems are solved.Indeed I have used factory Glock mags(2 of them). As I hinted at in the original post it wouldn't even peel the first round off after inserting a fresh mag. Since the post I disassembled the rifle, cleaned the **** out of it, polished the bolt, weight, and inside the tube with 1500 grit paper. Thereafter, I lubed it (left it wetter than I normally would) and reassembled. As a test, I inserted a mag with a couple rounds, released the bolt, ejected the round and did it again several times with no problems. Some more range time may tell if it was just a question of grit, burrs, and/or not enough lube. Should one be very generous in lubing up the bolt assembly on these rifles??????????
This worked for me. I added the heavy bolt as well as the Sumo handle. I also filed down the holes where the pin that holds the shoulder plate in place and the bolt stop. The holes were rough and were gouging the bolt when I was stripping to clean. These all completely changed how the gun shoots. Absolutely no functional problems since. Also, the added weight absorbs much of the recoil so it now feels like shooting a 22 in stead of a 40cal.I had case gouging issues as well. I strongly believe it's due to high bolt velocity with a .40 . The heavy bolt and sumo handle solved the issue. I guarantee you'll be happy if you do these two mods to your .40 sub2000.