A scope is a firearm accessory that assists the gunner in aiming and observing the bullet point. Its forms can be divided from basic to advanced: the simplest "rear sight + front sight" mechanical sight, fast sights represented by hologram and red dot, and the most advanced magnification optical/electronic sights.
The sniper rifle uses a high-magnification sight, which can magnify the target by 3 to 10 times and kill the target hundreds of meters away. As we all know, the scope and the barrel are not in a straight line, but in two positions parallel to each other - the scope is either installed on the side of the gun body or on the top of the gun body. But such a design does not affect the performance of the sniper.
Doesn't the bullet come out of the barrel? The aiming point of the bullet is higher than the starting point. Why can the scope that is not in a straight line with the barrel be able to "point where to hit"?
Trajectory
To explain the problem. First of all, we need to talk about what ballistic is. The flight path of the bullet is not a straight line extending from the barrel. After the warhead is ejected, air resistance will cause its flight course to deviate slightly to the right or left, while gravity will make it gradually fall, forming a parabola.
If you aim the barrel directly from the back of the gun, gravity will force the impact point to appear further down the aiming point at greater distances. Can't hit a distant target at all.
Therefore, the line of sight of the sight is not parallel to the barrel. Taking the mechanical sight as an example, its line of sight is "rear sight + front sight + target" three points and one line. Although the rear sight is on the gun body, the height from the rear sight to the axis of the barrel is greater than the height from the front sight to the axis of the barrel. The "two points and one line" from the front sight to the rear sight is called the aiming baseline. Diagonal lines where the barrel axes intersect.
The gunner adjusts the distance scale on the rear sight so that the aiming baseline intersects the bullet flight trajectory, so that the target can be hit. Generally speaking, the farther the distance, the greater the height of the muzzle lift.
Many older rifles have a vernier scale, like the 1903 Springfield. For example, the scale of the icon ruler is calibrated to 2850 yards, about 2500 meters. By elevating the muzzle, a greater arc is given to the path of the bullet. If you fold the ruler completely flat, you will get a notch specially set up for quick aiming at 100 yards on the battlefield.
Each gun comes with its own front sight and rear sight. The mechanical sight cannot be magnified, and can only be aimed at the target purely by staring at the anvil hole and the small front sight tip with the naked eye.
The visible distance of the human naked eye is limited. If a target is more than 400 meters away, it is difficult to tell whether it is a human or a dog, so what is the point of aiming? The combat distance of ordinary infantry is almost 400 meters. In order to annihilate the target 400 meters away, the optical magnification scope came into being.
Science can only help you so far. Once the bullet flies out, you can only pray for luck in the metaphysics—after all your calculations, the bullet will still go astray. When you see this, you will understand that shooting a gun is also a technical job, and sniping is by no means as simple as a ray from the barrel.