https://blog.thegunsandgearstore.com/polygonal-rifling-in-glocks-why-it-matters/ Don’t Shoot Lead Bullets through Glocks (Polygonal Rifling) – FACT Lead bullets can foul polygonal rifling very fast and create an obstruction before you finish shooting an entire magazine in some cases. When people talk about catastrophic failures, this would be it! Don’t Shoot Reloads through Polygonal Rifling – FICTION You can shoot reloads safely through polygonal rifling, but it needs to be Full-Metal Jacket (FMJ), Total-Metal Jacket (TMJ), or simply Jacketed rounds. This will prevent dangerous fouling, and then the rifling will work for you like it’s meant to do: higher velocities, more accuracy, and greater longevity. Glock is the only company that uses polygonal rifling – FICTION There are several firearm companies on the market utilizing this style of rifling:Glock, Heckler & Koch, Kahr Arms, Magnum Research, Tanfoglio, and CZ.