I'm new to glock, but I'm pretty sure it's a gen3. All the gen4 pistols online have a different grip surface, and mine definitely looks like the old pattern. Don't get me wrong I love the handgun, I just don't like getting hit in the face with brass. The jam was a feed error, it Jammed the round between the feed ramp and the slide. That's why I believe it was the ammo I was using. Not to mention glock's reputation for flawless feeding and extraction. I just hope different ammo doesn't throw casings in my face, because it is not pleasant.