Glock handguns have a reputation the world over for accuracy and reliability, which is why many international law-enforcement agencies have chosen the rather unattractive handguns as their primary sidearms. Occasionally however, despite the reputation for accuracy, there may come a point when the rear sights on a Glock pistol need to be adjusted left or right to correct a faulty aim. Fortunately, adjusting a Glock's sights is not an especially complicated process--though you will need a couple of tools to do it.
Fire several shots through the Glock before adjusting your sights so you know which direction you will need to adjust in order to restore the accuracy to the weapon.
Eject the magazine and pull the slide back several times to eject any shells that may have been in the firing chamber. It is always important that you unload your weapon before you ever attempt to do any work on it.
Clamp the Glock--sights facing up--in a padded vise. An unpadded vise will also do, but a padded vise is recommended in order to keep from marring the finish of the pistol.
Place the tip of your plastic drift or punch--and the punch or drift should be plastic for the same reasons that the vise should be padded--against the side of the rear sight base. Make sure you will be tapping the sight in the right direction. If your gun is firing to the left, you will need to tap at it from the right.
Strike the butt of your plastic punch or drift lightly with your hammer to adjust the sight in the desired direction.
Test-fire the Glock to determine if the accuracy has improved, then repeat Steps 1 to 5 as needed.
Some Glock sights are also able to be adjusted for height. These sights will have a small screw at the top of the rear sights. Turn this screw counter-clockwise to raise the sight, or clockwise to lower it.