HayesGreener
Ronin
"New gun owner" is a clue. In my experience, failure to fire is usually an ammo or gun failure, and failure to feed is due to out of spec ammo, damaged magazine, poor maintenance, or shooter induced malfunction. I have trained hundreds of officers with semi autos and have seen the problem many times over.
You seem to be on top of the lube and maintenance issue and it's a new gun. Let's eliminate the shooter induced question first, which is a grip issue and one of the most common causes of failure to feed or double feed. The recoil spring must compress enough during firing to store sufficient energy to return the slide sharply into battery. If your grip is not firm enough, the entire gun is recoiling and the recoil spring is not compressing fully. It has to have something solid to push against. It is so common that we have a name for it-"limp wristing". The average shooter will begin to lose their grip on the pistol after 3-4 rounds of centerfire ammo. Your statement that the trouble starts after 4 rounds or so is a flag to me. Insufficient lube, a dirty gun, or under powered or out of spec ammo can cascade the effect. The point at which guns will fail to feed from limp wristing varies from gun to gun and from shooter to shooter. I see it mostly with lighter weight polymer framed guns. Some guns that are temperamental to begin with are more susceptible. The simple test is to have an experienced shooter who is aware of what is going on run a couple magazines through the gun.
You seem to be on top of the lube and maintenance issue and it's a new gun. Let's eliminate the shooter induced question first, which is a grip issue and one of the most common causes of failure to feed or double feed. The recoil spring must compress enough during firing to store sufficient energy to return the slide sharply into battery. If your grip is not firm enough, the entire gun is recoiling and the recoil spring is not compressing fully. It has to have something solid to push against. It is so common that we have a name for it-"limp wristing". The average shooter will begin to lose their grip on the pistol after 3-4 rounds of centerfire ammo. Your statement that the trouble starts after 4 rounds or so is a flag to me. Insufficient lube, a dirty gun, or under powered or out of spec ammo can cascade the effect. The point at which guns will fail to feed from limp wristing varies from gun to gun and from shooter to shooter. I see it mostly with lighter weight polymer framed guns. Some guns that are temperamental to begin with are more susceptible. The simple test is to have an experienced shooter who is aware of what is going on run a couple magazines through the gun.