I go the new Gen 4 17 put over 500 rounds through it using American Eagle, Remington UMC, and Federal Champion(all 115 grain). Not one single malfunction. It worked perfectly. My dads gift for my mom was the 20C. That Glock is unbelivable. It is so easy to control. We did some night firing and the muzzle blast is awesome coming off of the 20C. It was a wonderful Christmas weekend!!!