I have a G19 gen3. The accy. rail on the frame had an upward slant that caused a problem with my laser acuracy. The laser was only on target for about 3'+or- from the distance it was set for. Any further out and the laser was too high. so today I decided to attempt a repair, and it worked. I took two flat washers that were the correct thickness to level out the accessory rail and opened the gap with a screwdriver and inserted them between the slide and the frame...The gap was almost closed at the front of the gun. The washers held the correct spacing. I then heated the front of the frame with a heat gun. This caused it to take the "set" created by the washers. After the frame cooled I removed the washers and the gap was now permanent and the rail was level. This has bugged me for a while and today I decided to do something about it. I have seen other glocks with this same condition, so I thought I would share my results. Obviously don't get crazy with the heat, but it worked for me..