Just recently , Glock 17 occasionaly has a light strike in primer ( small dent ) and fails to fire ., so have to eject. Also noticed that when this happens the slide sits back maybe 1/8" but why does this happen . Firearm clean and in good condition , ammo ok , have used other shooters ammo , have had other shooters use and inspect firearm . Had a lot of suggestions but can't seem to find or fix problem . Problem does'nt seem to have a rythem as to when it happens Any suggestions ?