Originally Posted by otisthecat
But would any of that still cause it to happen when not shooting? I'm honestly not trying to be sarcastic, I really don't know. I have only put 80 rounds through it, maybe it will work itself out with another trip to the range. Works out fine as my LGS is also my range, so I was going back tomorrow one way or the other.
Easing the slide forward would be similar to not having the gun held firmly or dragging the thumb on th eslide, because they all slow down slide velocity and could cause the slide to fail to return to battery.
The reason I had asked earlier about the cleaning, is because Glock puts some grease on the frame rails that ride in the grooves of the slide. This copper colored grease helps in initial break-in and should be left on the rails for the initial shooting. It should still function even if you cleaned it off, but it could also give you some of what you are experiencing, early on until your round count is higher.
Also, the recoil spring could be an issue, but it shouldn't be on a new gun.
I use pretty hot ammo early on when shooting a new pistol to ensure that the action gets enough force to cycle until it is broken in a bit.
Many will argue that a new modern gun shouldn't need to be broken in (I don't think that they should need it either) but I still have a habit of running warmer loads in teh beginning.