After the proper range (elevation) and windage (deflection) have been set on the sights, they must be properly aligned with the target. This is done by manipulating the T & E mechanism.

SIGHT ALIGNMENT.- To align the sights of the M60 machine gun correctly, center the front sight blade vertically in the aperture of the rear sight slide. The top of the front sight blade should be even with the top of the rear sight slide (fig. 13-31).

SIGHT PICTURE.- With the sight properly aligned, obtain a 6 o'clock sight picture on the target (fig. 13-32). Always aim at the center base of the target for your initial burst of fire. When shooting at enemy personnel, aim at their beltlines.

Figure 13-33.-The .50-caliber Browning machine gun (BMG), M2HB.

ADJUSTMENT OF FIRE

Adjustment of fire is the second fundamental point of good marksmanship. Both the team leader and the gunner must observe the strike of the bullets from the initial burst. They must be able to evaluate and adjust their fire rapidly if they are not on target. When firing the biped-mounted gun, you adjust fire by changing the position of your body. When firing the tripod-mounted gun, you adjust fire by manipulating the tripod traversing and elevating handwheel.

ZEROING-IN

Zeroing-in the M60 is similar to zeroing-in the service rifle. Three rounds are fired at a target with a predetermined range, generally of 500 meters. The rear sight is set to 0 windage and to the corresponding range (500 meters). After the three rounds are fired, the center of the group is estimated. Next, adjust the windage knob on the rear sight, as required, bringing the strike of the bullet to the vertical center of the bull's-eye. One click clockwise or counterclockwise of the windage knob is a l-mil adjustment. This means that at 500 meters one click will move the strike of the bullet 18 inches either right or left. Next, you must change the elevation, if required, by turning the elevation knob. A one-click adjustment clockwise or counterclockwise of the elevation knob equals a l/4-mil change. At 500 meters this would be 4 1/2 inches.

With the correct adjustments made to the rear sight, the T & E mechanism is manipulated until the correct sight picture is again obtained. You then fire one round to confirm your sight setting. If the round misses your point of aim, you must repeat the above procedure, making the necessary adjustments until the bullet strikes where you are aiming.

After the final adjustments are made, putting the strike of the bullet at the aiming point, you must adjust the rear sight range plate. To do this, loosen the screw and move the plate until the 500-meter range mark coincides with the top left edge of the rear sight slide. Tighten the range plate screw and then record the amount of deflection for future reference.