Gamo is a manufacturer of precision air rifles. Unlike the BB and pellet guns designed for kids, Gamo rifles are designed for serious sportsmen and precision shooters. Therefore, all Gamo rifles are equipped with adjustable sights, allowing shooters to adjust for such factors as distance and individual preference. Gamo produces many models of air rifles, some of which are equipped with optical sights. Individual rifles may vary slightly, but shooters can apply the basic procedure to all Gamo air riles with iron sights.
Arrange a shooting area that allows you to fire the rifle from a supported position to a distance of 10 yards. The firing position doesn't matter as long as the rifle is supported and the firing conditions can remain stable.
Place a paper target down range. A paper target will allow you to observe the strike of the pellet and make adjustments accordingly.
Aim at the centre of the target and fire three shots. Where the pellets strike at this point is not important. What is important is that all three shots land very close to one another. This provides a grouping that takes into account slight variations in accuracy caused by factors such as wind, breathing and firing position.
Relax from the firing position. Re-assume the firing position and fire three more shots. You should now have a good starting point from which to sight-in the rifle.
Check the target and measure the distance from the centre of the two groups to the centre of the target, both left to right and up and down. Mark the group to distinguish it from future groups, and return to the rifle to make adjustments.
Turn the adjusting screw on the right side of the rear sight one click clockwise for every inch the shot group was to the left of the centre of the target, or counterclockwise for every inch the group was to the right of centre.
Turn the adjusting screw on the top of the rear sight one click clockwise for every inch the shot group was above the centre of the target, or counterclockwise for every inch below centre.
Fire three more shots at the target and recheck. Repeat the procedure in steps 6 and 7 to further adjust the sights. Continue the procedure until the three-shot group strikes the centre of the target.
The standard distance for sighting an air rifle is 10 yards. However, Gamo rifles are capable of accuracy much farther than that. If you intend to fire at targets farther than 10 yards, you should adjust the distance at which you sight in the rifle.