Comparison Discovery VT-R 3-9x40 vs Discovery VT-Z 3-9x40

The diameter of the area visible through the sight from a distance of 100 m — in other words, the largest distance between two points at which they can be seen simultaneously from this distance. It is also called "linear field of view". This indicator is more convenient for many users than the angular field of view (the angle between the lines connecting the lens and the extreme points of the visible image) — it very clearly describes the capabilities of the device.

In sights with magnification adjustment (see above), both the entire range of width — from maximum to minimum — or only one value of this parameter can be indicated. In the latter case, the largest width of the field of view is usually taken, at the minimum magnification.

Units of measurement of angles used in the scope - primarily for making corrections using the drums. The same units are often used in marking the goniometric elements of the aiming reticle (see “Measuring units of the reticle”), but there are exceptions, so it would not hurt to clarify this point separately. Nowadays there are two main units:

- MOA. Abbreviation for minute of arc - 1/60th of a degree. Originally, this unit is associated with the English system of measures and is convenient primarily for calculations in yards and inches: at a distance of 100 yards, an angle of 1 MOA corresponds to a linear dimension of approximately 1 ". In the metric system, which is more familiar to us, this gives 2.91 cm at a distance of 100 m. We also note that this unit is a kind of accuracy standard: it is believed that a full-fledged sniper rifle should give a spread of no more than 1 MOA.

—MRAD. The symbol for a milliradian is an angle of one thousandth of a radian (approximately 0.06°). Also in sniper jargon, this unit is called “thousandth”, or “mil”. It is already tied to the metric system: at a distance of 100 m, an angle of 1 MRAD corresponds to a linear dimension of 10 cm (approximately 3.5 times more than 1 MOA).

The choice based on this indicator largely depends on the personal preferences of the shooter. And although “thousands” are generally more convenient for domestic use...rs, with minimal experience you can successfully use MOA, and also switch between these units and convert one to another without much difficulty. So in general this point is not particularly important.

The division value of the turrets used in the sight to enter corrections.

The increment value for the correction turret is the angle that the point of impact shifts when rotated by 1 click (“click”). In this case, this angle is indicated in MOA — minutes of arc. For more information about this unit, see "Measuring units of the sight"; and the lower the division value, the more accurately you can set up the sight initially and make corrections in the future. For example, if this indicator is 0.5 MOA — each click will shift the point of impact by about 1.46 cm for every 100 m of distance (that is, 2.91 cm at a distance of 200 m, 4.4 cm at 300 m and so on); and 0.25 MOA will already give only 7.3 mm per click for every 100 m.

The smaller the step and the more accurate the adjustment system, the more expensive it is. Therefore, when choosing, it is worth taking into account the features of the planned application — first of all, the size of the targets and the distance to them; detailed recommendations on this matter are in various manuals on shooting. If we talk about specific values, then the mentioned 0.5 (1/2) MOA are typical mainly for inexpensive and medium scopes, 0.25 (1/4) MOA is a pretty good indicator, and the advanced optics itself allows adjustment in increments of 0.125 (1/8) MOA.

The division value of the turrets used in the sight to enter corrections.

The increment value for the correction turret is the angle that the point of impact shifts when rotated by 1 click (“click”). In this case, this angle is indicated in MRAD — milliradians, or "thousandths" ("mils"). For more information about this unit, see "Measuring units of the sight"; and the lower the division value, the more accurately you can set up the sight initially and make corrections in the future. It is worth recalling here that for east european shooters the “thousandth” is convenient because this unit is directly related to the metric system: 0.1 MRAD corresponds to 1 cm at a distance of 100 m. So, for example, a division value of 0.2 MRAD allows at a distance of 100 m, shift the point of impact by 2 cm with each click; at 200 m this shift will be 4 cm per click, at 300 m it will be 6 cm per click, and so on.

There are also more subtle adjustment systems, with a division price of already 0.1 “thousandth”. At the same time, note that the smaller the adjustment step, the more expensive the mechanics of the sight. Therefore, when choosing, it is worth taking into account the features of the planned application — first of all, the size of the targets and the distance to them; detailed recommendations on this matter are in various manuals on shooting.

The type of mount supplied with the scope.

For normal mounting on a weapon, this mount must match the type of seat for the scope. The most popular types of mounts nowadays are on the Weaver / Picatinny rail and on the dovetail ; branded latches are noticeably less common, and some sights are supplied without mounts at all — this allows you to choose the option at your discretion. Here is a detailed description of specific options:

— On the Weaver / Picatinny rail. Fastening on a standard bar (“rail”) Weaver or Picatinny rail. It is considered the Western standard for installing a weapon body kit, but nowadays it is widely used around the world. It is worth noting that these types of slats, although similar in design, are not the same. They both have a T-shaped profile and transverse slots that allow you to securely fix the installed accessory in the chosen place, but differ in the size and location of these slots: they are wider in Picatinny rails and have a standard distance between centers. In fact, this leads to the fact that accessories for Weaver rails can easily fit on Picatinny rails, but not vice versa. In addition, Picatinny is considered more of a military standard, and civilian weapons are equipped mainly with Weaver rails. Thus, most of the complete rail mounts found among modern sights are designed specifi...cally for the Weaver rail, as it is more common and universal. However, exceptions are possible, so this nuance needs to be specified separately.

— "Dovetail". The seat of this type has a cross-sectional view of an inverted trapezoid, and the mount provides protrusions on both sides, which, when the sight is installed, “cover” this trapezoid. This type of mount is found mainly in air and sporting rifles, as well as in hunting weapons of a classic design. In the latter case, this choice is also due to aesthetic considerations — these mounts look neater than the gear "rails" of Weaver and Picatinny rails.

— Firm. Various specific fastenings not related to the standards described above. Often they are made not just for the products of a particular brand, but also for strictly defined models of weapons; one of the characteristic examples is the original seat on the high-end "sniper" Blaser R93. Branded devices can have a rather original design — for example, in some collimators for shotguns, a plate is used that is fixed between the butt and the receiver. In general, due to limitations in application, such fasteners are usually provided not as the only option, but as one of the options, in addition to the bar and/or dovetail.

Separately, it is worth touching on situations where several types of mounts are indicated in the characteristics of the sight at once. Most often this means that this model is available in different configurations, but there are other, more specific options — the presence of several types of mounts in the kit at once, an adapter from one type to another, or even a universal retainer that is also compatible with Weaver / Picatinny rails, and with a dovetail. Such details in each case should be clarified separately.