This is a question for Glock Gen 4 owners. Glock haters or Gen 4 haters please do not respond.
A shooter came to the range today with a brand new G19 Gen 4. For the first several rounds (4-5) of each magazine the slide would stay back after each round was fired. The slide was not locked back, the slide release was in the down position. It was not a magazine issue as we tried a well used magazine from another shooter who had a Gen 2. After the first 4 to 5 rounds were fired the slide would retract and then hesitate before going into battery for about the next 4 rounds. After that it would fire the remaining 5 to 7 rounds like a champ. We did not swap the recoil springs between the Gen 4 and the Gen 2 model because I did not think of it. Any Gen 4 shooters encounter this or anyone have an idea of the problem?