Regardless of the problem you shouldn't have taken sandpaper to the slide lock without knowing what your doing. You can clearly see in the video you are barely moving the gun with your hand nowhere near the slide release and the slide released all on it's own. Even if you did not take off that much material you could have changed the angle. Some guns from repeated use of the slide release over time can wear just enough material off where the slide fails to lock back, so taking sandpaper or a file to it really isn't the best idea. It does nothing to make the gun inoperable but during a high stress mag change when that slide releases all on it's own it could screw you.
Last edited by Dragline45; October 20, 2012 at 10:24 PM.