Air guns, designed on the basis of this principle is the most massive - in the world there are millions of such guns. It would be a mistake to assume that mass is not only simple, low cost of production, but also low efficiency. On the contrary, the most expensive model airguns, characterized by high accuracy of fire, made precisely on the basis of this principle.
In air guns of this type is used moving the piston in the cylinder due to the energy of compressed spring. Cylinder, usually located in the butt, and one end is connected to the trunk. When cocking the gun piston, overcoming resistance of spring, moves to the rearmost position, in which is fixed. At this point, the spring is maximally compressed.
When you press the trigger a powerful spring, straightening, pushing the plunger forward, thereby increasing the pressure in the cylinder. As a result, the pressure difference arising ejected pillar of compressed air pellet, located in the trunk, starts his movement.
At the speed of a pellet is affected by many factors, chief among them are the speed of the piston and its power, as well as the amount of Displaced air. It is also necessary to note such factors as weight and dimensions of the pellet, as well as an air leak as a result of gapping piston to cylinder wall and a pellet to the barrel.
When the gun is cocked, the lever mixing piston in the rearward position, resulting in a compression spring with a force of about 27 kg. As a result of pressing the trigger the plunger by the spring mixes ahead at a distance of just over 5 cm at a velocity of the piston is more than 12 m / sec. You may ask, why then the initial velocity of a pellet, vypushennoy of pneumatic weapons of this type, more than 100 m / s?
Need to understand that no spring and the piston attached to the pool faster. pellet pops out of the barrel column of air. Since the entire volume of the compressed air cylinder can leave only through a narrow bore, here come into force the laws of gas dynamics and is accelerating the movement of the air column, which in practice means: air kanale barrel moves faster than the air just before the piston in the cylinder. The air pressure must reach a certain size, to move a pellet from the place, breaking the force of inertia, friction and the amount of resistance experienced by a pellet while entering the bore. Prior to the start of the piston motion pellet passes not more than 1,25 cm This means that the pressure reaches values exceeding 2000 kPa. Even after the piston has stopped the movement, the compressed air continues to move the pellet to the barrel. At the time of stopping the piston velocity of the pellet reaches 53 m / s, passed in the barrel length is 5 cm in this time of the air pressure reaches a peak, making the passage through the barrel following 7,5 cm pellet accelerates to 90 m / s but in escaping from the barrel, its velocity is about 100 m / sec.
Of course, different models of airguns (and especially the expensive models), produced by different firms can have different characteristics from those listed above. For example, the catalog company Faynverkebau (FRG) is a model air rifle c 124, having the following characteristics: initial pellet velocity - 270 m / s, the force of compression springs - 260 kg.
To perform this type of weapon cocked rifle used levers. If the air rifle has a powerful spring, then for her platoon requires more effort. In this case, to increase the lever arm to connect with the barrel, thus achieving the necessary force to compress a powerful spring. There are models of airguns and other provision of the cocking lever spring. The barrel on these models are firmly fixed and is not associated with a lever cocking. The lever is located half a cylinder or the side of him. Such a system is installed at a sporting air rifles high class, for example, "Faynverkebau" model 300. It should be noted that this type of air gun is characterized by stability such thing as pellet velocity. A stable speed of a pellet, in turn, ensures accuracy.
But this type of airgun, and certain inherent deficiencies that adversely affect the accuracy of hits. This is, first, hard descent, caused by the presence of a durable mechanism that holds the powerful spring in a compressed state. This shortcoming will feel like a cheap American guns, and in the expensive models, produced in Europe. Obviously, this problem can be solved only by introducing into the design of complex systems mnogorychagovogo trigger mechanism, which would inevitably entail a rise in the product.
The second disadvantage is largely affects the accuracy of contact - a tangible output, create a powerful spring and piston. To eliminate the negative effects of the recoil use special devices. Some of these devices so effectively dampen impact that it did not feel it. Of course, the massive weapons they are not equipped. These devices are installed mainly on sporting arms. Consequently, its price rises to 600 or more dollars.