I had a few misfires in my Glock 19. The firing pin did not strike the primer hard enough to ignite the ammo. I looked at other shells which were fired and they looked fine. A good cleaning of the gun helped but it happened again. It happened about four times with PMC ammo and once with Remington 115 grain FMJ. I have about 2000 rounds on the gun and just wondered if I need to replace the plunger spring or something else.