The most important factors involved in correct sighting and aiming are proper sight alignment and a correct aiming point. Together they make up the sight picture.
Sight alignment is the art of looking through the rear sight aperture, focusing the eye on the front sight post (or blade), and centering the front sight post exactly in the rear sight aperture both vertically and horizontally. The body of the front sight post, or blade, is centered vertically. The tip of the front sight post, or blade, is centered horizontally within the rear sight aperture (see figure below).
Rear Sight - In each firing position (prone, standing, kneeling, and sitting), the aiming eye is at a slightly different distance from the rear sight. This distance, refereed to as eye relief, causes the opening (peep) of the rear sight to appear larger or smaller, depending on the firing position. Regardless of the apparent size of the rear sight opening, the front sight must be aligned in the center of the opening. It is important to keep your eye the same distance from the peep sight in any particular firing position. To ensure this distance is always the same, you must hold the rifle in the same exact location for each shot. This location is commonly called the SPOT WELD, or anchor. There are several tricks shooters use to help them maintain this distance. One is to place a small piece of tape on the stock of the rifle where it touches the cheek. In this manner, the shooters can feel whether their cheek has the proper eye relief.
6 o'clock sight picture held on an "D" target at a range of 200 yards.
6 o'clock sight picture held on a "A" target at a range of 200 yards.
Front Sight - The front sight always appears to be the same size. However, depending on the distance your eye is from the rear sight, more or less of the front sight may be visible in the sight picture. The front sight, not the target, is the point of focus for the eye; and as such, it will be sharp and distinct in outline. For this reason, keep the front sight square, leveled, and blackened.
Aiming Point - The aiming point is that point on the target upon which the sights of the weapon are brought to bear. The correct aiming point is at 6 o'clock; that is, the bottom of the bull's-eye of a type "A" target or the silhouette of a type "D" target. Any location on the target face is always given relative to a similar position on a clock face regardless of the target shape. Therefore, a vertical line in the exact center of the target would be described as running from 12 o'clock (top) to 6 o'clock (bottom).
Sight Picture - You obtain the correct sight picture by aligning the rear sight, the front sight, and the bull's-eye. Each of these three elements affects the sight picture. As you can see from the figure, any error in sight alignment will increase as the range increases. An error in the aiming point remains constant as the range increases. Therefore, of the two, sight alignment is the most important.
At close ranges, the bull's-eye or silhouette will appear larger in relation to the front sight, than it will at longer ranges. This means that the sight picture will vary not only from one firing position to another but also from one firing line to another.
Error in sight alignment increases as range increases.
Variation in sight picture for each range of fire.
Training - You should train in aiming along with the position and trigger squeeze before actually firing on the rifle range. You do this by aiming at a series of small bull's-eyes at least 20 feet away on a "dry-firing" range; this training is known as "snapping in."
Blackening Sights - You should blacken the sights during sighting and aiming exercises to help eliminate light reflection or glare. Blacken all sights, both front and rear, on the base of the receiver and the top of the barrel. The usual way of blackening a sight is by means of a smudge pot, carbide lamp, oily patch, candle, cigarette lighter, or ordinary match. Be sure to remove all oil from the sight before blackening it.