Wolf primers are harder than woodpecker lips. There was one Wolf primer that didn't go on the first lick. It looked like a solid hit to me. It lit off when put through the gun a second time. Up to you whether you want to hang that on the primer or the gun.
That makes 250 rounds through the Gen4 19 since it was cleaned or lubricated with one failure-to-fire (#205). 1,750 rounds to go.
External differences between the Gen4 Glock 19 and its "Gen3" predecessor. If you ask me, the biggest difference between Gen4 guns and earlier models is that, for the first time since 1990, the .40 cal and 9mm Glocks have different recoil spring assemblies.
.