I have a question about Glock brand sights. On my Glocks, on the front sight they have the screw from the underside. However, I went with a friend this past weekend to a gun show and he bought a used 22 and 19. The 19 looks like the front sight is the plastic sights that just snap in. His 22 has some off brand night sights that look staked in but that has no relevance to my question. I was just kind of shocked they would not also be screw in. Is there a way to tell if you have the steel sights or polymer sights on a new glock?