Muzzle energy
The muzzle energy provided by the rifle.
Muzzle energy is the kinetic energy of the bullet at the exit from the barrel. This energy, in turn, depends on two factors: the mass and the muzzle velocity of the bullet. Thus, this indicator directly describes the overall power of the rifle: higher muzzle energy allows you to effectively fire at longer distances and/or heavier ammunition. On the other hand, an increase in power accordingly affects the cost of weapons.
Note that muzzle energy can be grounds for legal restrictions on the purchase/use of pneumatics. So, in some countries in the post-Soviet space, the maximum value allowed for freely sold rifles is
7.5 J — a special permit will be required to purchase more powerful weapons. And most freely sold rifles in such regions have a power of the
order of 3 – 5 J. Such legal restrictions should be clarified separately. Lower rates are found mainly among “soft” pneumatics for airsoft (airsoft), using 6 mm plastic balls. For such models, a value of more than 2 J is already considered very solid, and in games such rifles are used with a minimum distance limit — for example, 15 m or 20 m (so that a shot from too close a distance does not injure the player).
It is also worth saying that the claimed characteristics of air rifles may, at first glance, not correspond to physical calculations. For example, for a model for the same 7.5 J
..., the initial speed of 250 m/s can be claimed in the characteristics; for a 4.5 mm bullet weighing 0.5 g (the average, most popular weight), this would correspond to an energy of as much as 15.6 J. However, there are no inconsistencies here: such characteristics mean that the muzzle velocity was measured for a lighter bullet (for example, 0 .2 g), which accelerates more strongly at the outlet of the barrel. Accordingly, with heavier ammunition, the speed will be lower; it can be determined using special formulas or online calculators.Swivels
The presence in the design of the rifle
sling swivels — special loops or staples (usually metal) on which the weapon belt is attached. There are usually two such loops — in the front and back of the weapon. In this case, most often the swivels are installed on the underside of the butt and forearm; this design is universal, it allows both right-handed and left-handed people to use the belt with the same comfort. There are also models with a lateral location of the front swivel — usually on the left side of the forearm, under the right-handed hold; however, nowadays in such rifles it is often possible to rearrange the swivel to the other side. So if the pneumatic is bought for a left-hander and it is planned to equip it with a belt, it will not hurt to clarify the features of the sling swivels separately, however, most likely, their design will not create inconvenience.
Magnification
The degree of magnification provided by the rifle's complete optical sight; for models with variable magnification, the entire adjustment range is indicated, for example 3 – 9x.
For sights of this type in general, see "Aiming Device". And several points depend on the degree of increase at once. On the one hand, a higher magnification allows you to better see small and/or distant targets and facilitates high-precision shooting; on the other hand, it limits the angle of view and significantly affects the cost of the sight, and sometimes also its dimensions and weight. And since air rifles are mostly not designed for long distances, the magnification of complete optics in them usually does not exceed 9x, and one of the most popular options is 4x. However, there are exceptions: in powerful high-end pneumatics, you can find sights with a maximum magnification of 24x and even higher.
Actually, the manufacturer most often selects the magnification of optics for the ballistic characteristics of the rifle. So, when choosing this parameter, it often turns out to be secondary, and it makes sense to focus primarily on the muzzle velocity of the bullet and the firing range for which the weapon is designed — usually, the capabilities of complete optics are quite enough for this. It is also worth mentioning the variable magnification sights mentioned at the beginning, which are quite common nowadays — they are somewhat more complicated and more expensive than fix...ed optics, but they allow you to adjust the magnification to the specifics of the situation.
Lens diameter
The diameter of the front lens (objective) in the optical sight, which is equipped with a rifle.
For sights of this type in general, see "Aiming Device". And the diameter of the lens depends primarily on the amount of light entering the scope. Thus, other things being equal, a larger front lens produces a clearer and brighter image; this is especially noticeable in low light. On the other hand, a larger lens is noticeably more expensive, and it also affects the weight and dimensions of the sight; and in bright daylight, the difference from the “smaller” optics may not be fundamental. In addition, recall that the actual image quality is determined by a number of other factors; as a result, high-end optics with a relatively small front lens may well be more effective than a large low-cost model.
In view of the foregoing, it is worth paying attention to the diameter of the lens in cases where the sight is planned to be used in low light conditions — in a dense forest, at dusk, etc. In this case, it is worth considering not only this indicator, but also other features of the optics (and it is best to focus on practical reviews). If the rifle is bought for recreational use in the daytime in good light, the size of the lens will be a purely reference parameter: in such conditions, almost any optical sight works normally.
Scope mount diameter
The diameter of the mounts that the complete optical sight of the rifle is equipped with. For optics in general, see Sights. And the diameter of the mounts is the diameter of the rings in which the tube of the sight is fixed. These rings are mounted on brackets, with which the entire structure is attached to the rifle.
In the vast majority of cases, the diameter of the rings is a purely reference parameter that does not affect the choice. Before buying a rifle, this data may be needed if the "household" already has another optical sight, which may be used instead of the standard one. And even in such cases, usually, it is easier to use the "native" mounts of a spare sight than to install it in the rings from the complete optics.
Also note that the vast majority of pneumatics with optical sights use mounts of a standard diameter — 25.4 mm. Other values (for example, 19 mm) are extremely rare.
Barrel length
The working length of the rifle barrel is from the chamber where the bullet is loaded to the muzzle. The shortest barrels found nowadays have a length
of just over 200 mm(and in some AEGs even
less than this value); the longest reach
500 – 600 mm.
There is a stereotype that the muzzle velocity directly depends on the length of the barrel. In firearms, this is true — but not in pneumatics. Firstly, in such rifles, the initial velocity depends on a number of other indicators — pressure, the quality of the barrel treatment, the efficiency of the valves, etc. on the first 20 – 25 cm of the barrel, then the gas pressure drops noticeably. The exception is PCP rifles, in which the longer barrel really makes it easier to achieve high speeds. However, again, so many additional factors affect the final result that models with the same barrel length can differ markedly in initial speed.
The second common stereotype is that a longer barrel improves accuracy and accuracy. This is true in the context that a longer barrel allows for a greater distance between the front and rear sights, making it easier to aim carefully. Technical accuracy does not depend on the length, but on the quality of the barrel processing.
Summing up all of the above, we can say that the length of the barrel for an air rifle is more of a reference than a really significant paramete
...r, and when choosing, it is better to focus on more "close to life" characteristics — first of all, directly claimed muzzle velocity.