I'm a nooby and. How can you tell what generation of Glock Do I have? I have just made my first purchase from a policeman. And he has had it for 12 years. I looked at his brand new Gen 4 and I couldn't tell much difference. I know that the grip is interchangeable on the four and I like a place to put my pinky on the mag but I couldn't tell any else that was different. Thanks Jeff Wanna kill these ads? We can help!