In the four months or so I have owned my Gen4 23 I fired more than 1200 rounds of a variety of high quality FMJ and JHP ammo with ZERO malfunctions. Early on I customized it a bit. First was a Glockmeister tungsten RSA. Then your basic extended slide lock and take down levers and other minor upgardes. Then a Travis Haley SKIMMER carry trigger, stainless pins, etc. Then a ACS tritium extractor. All of these things were done within the first 4 or 5 hundred rounds and I had at least 600 beyond the last mod with still ZERO malfunctions. Then recently I replaced the stock barrel with a Lone Wolf stainless steel (standard length). I had nothing but problems with it. Loads of feed/FTF malfunctions. I contacted LW and they asked me to send the barrel back to them. Unfortunately, I don't still have their email that told me exactly how the "fixed" it, but they basically filed and polished and tested and sent it back. Here's where it gets interesting... When I got it back I put another 200+ rounds of my usual target ammo, which is the flat-nosed stuff fmj mostly Federal 165 or 180 including American Eagle. I had ZERO problems and was very happy. Then I shot two days in a row as part of a class where I fired about 100 per day. Zero problems the first day, but then I didn't clean it before second day and I had the same malfunctions* again. Because it was a class after one or two problems I quickly put the stock barrel back in and, of course, had no problems. By this point I had about 1400 rounds through the stock barrel with ZERO problems. Here's where it gets more interesting... or weird. So today was my first day at the range since the aforementioned class a couple weeks ago. The gun was thoroughly cleaned and I had put the LWD stainless barrel back in. I started having the malfunctions right away. I'd shoot a half dozen shots and then nothing. No click. Not reset. Nothing. No boom. I'd TAP, RACK, ASSESS. Shoot another round, maybe two and then same thing. Nada. After the last shot the slide goes back, but you can feel right away that there is a problem. Today I took the LWD S/S barrel out and could see a metal shaving - a thin circular piece of the barrel circumference - at the feed ramp. I got to talking with the range officer and he wanted to blame the flat nosed FMJ .40 rounds. I told him that after the barrel was "fixed" and returned to me that I shot a couple hundred without problem. Regardless, I put the stock barrel back in to keep shooting. That was when I became real frustrated. For the first time ever, I started having the same problem with the stock barrel. Before switching was an immediate and permanent fix. Now I had exactly the same thing happening with the same frequency with the stock barrel. It seems the other malfunctions had done something non-barrel related that now affects using the stock barrel as well. Anybody have any ideas? Obviously I am disappointed with the LWD barrel. They were quick to remedy before so I am sure they'll help me again. But to have problems now with the stock barrel in my favorite gun sucks. Guess I'm looking for a gunsmith, but I am interested in feedback. If you read all of this, thanks for your patience!