I am really puzzled with this one. I have a Gen 3 model 17 that has performed flawlessly until now. I purchased the gun new and have run about 700 rounds thru it. I push in a new magazine and it locks but now when I fire it, I have the clip drop out of the bottom. I have tried several different magazines and have the same problem. Before you ask, I am positively not hitting the release with my thumb. Can anyone advise how to fix this as I really like the weapon?