The best long-range rifle scope will be one that suits your individual needs and preferences. When choosing between long-range rifle scopes consider the level of magnification, whether the scope is variable or fixed, the size of the objective lens, the scope tube size, and the field of view. Other things to consider include adjustable objectives and the minutes of angle (MOA).
First, you should learn how to identify a long-range rifle scope, as this will help you choose a scope that will offer the magnification you need. Scopes are generally identified by their magnification range and the size of the objective lens. For example, a scope that bears the marking 3-9 x 40 offers magnification levels of three to nine times and an objective lens of 40 mm in diameter.
The magnification range is one of the most important considerations when choosing a long-range rifle scope. The higher the magnification the less light the scope will transmit, though a lens coating can improve contrast and counteract glare and loss of light through the scope. High magnification ranges can also limit or narrow the field of vision.
Also consider whether you would like a variable scope, which has an adjustable magnification range, or a fixed long-range rifle scope. If the scope is marked 3x-9x, for example, it means that the scope can be adjusted to anywhere between those values. The 3x-9x range scopes are generally used for a deer rifle. Fixed scopes offer just one level of magnification, which makes them less flexible, though some individuals prefer them due to their simplicity and ease of use. If using a fixed scope, consider the distances you would prefer to use the scope at.
The size of the objective lens is also important, especially when choosing a high power or high magnification rifle scope. The larger the objective lens, the more light it will collect, and this makes it a good option when you would prefer a clearer view at higher magnification levels. The objective lens is normally identified by its size in diameter. An objective lens of 40, for example, would refer to a lens that is 40 mm in diameter. It is important to remember that while a larger objective lens creates a better view overall, it also makes the lens heavier and larger which can complicate the mounting process.
You should also consider the tube size when looking to purchase a long-range rifle scope. The tube size is designated by diameter, and most scopes will feature a main tube in sizes of 1 inch (about 2.5 cm) or 1.18 inches (about 3 cm). Knowing the tube size is especially important because the tube size will determine what size rings you need to mount the scope.
Field of view (FOV) refers to the area you are able to view while using the scope. It is the measurement of the view, left to right, when looking through the scope at a set distance. The field of view measurement is normally taken at a distance of 100 yards (about 91.44 m), and as magnification is increased the field of view decreases.
Adjustable objectives refer to adjustments that can be made to the objective lens, normally to counteract parallax. Parallax refers to the placement of the eye in relation to the scope, as the eye will not always be in the same position every time the scope is used. The objective lens can be adjusted to compensate for this.
Minutes of angle refers to a feature on a long-range rifle scope that allows the adjustment of the point of impact. If, for example the bullet is 1 inch (about 2.5 cm) low at 100 yards (about 91.44 m) four clicks would be needed to adjust the minutes of angle. Adjustments are normally made in increments of 1/4 inch (about 2.5 cm) at 100 yards (about 91.44 m).