多数充气式气枪的高压容器内的压力随着射击次数的增加而减小。为了消除影响弹丸枪口速度的这一变量,采用每次射击后补充充气的方法,使充气式气枪具有相同初始发射能量。以不同的射击距离发射材料密度不同的三种同径球形弹丸,测量弹丸的速度,计算弹丸的动能及比动能。在射击距离为30 cm时,钢珠的比动能是塑料弹的比动能的1.59倍;在射击距离为400 cm时,钢珠的比动能是塑料弹的比动能的2.02倍。分析同一射击距离上不同质量弹丸的速度、动能和比动能的变化规律以及弹丸速度和比动能随射击距离的变化规律,结果符合内弹道学有关推论,得出“同径球形弹丸材料的密度越大,在相同射击距离上的比动能越大”的结论;为进一步规范气枪枪口比动能测试工作提供理论及实验依据。

The air reservoirs of most BB guns release a fraction of their pressure following the firing each time. To avoid the influence of this variable on the muzzle velocity of projectile, the air reservoir is usually re-filled after each firing so as to ensure that a pneumatic gun maintains the same muzzle energy. Here, after three diameter-same spherical projectiles of various density were fired at different distances, the velocity of the projectiles was measured and their kinetic energy and specific kinetic energy were calculated. At a firing distance of 30 cm, the specific kinetic energy of a steel projectile is 1.59 times as many as that of a plastic projectile. At a firing distance of 400 cm, the specific kinetic energy of a steel projectile is 2.02 times as many as that of a plastic projectile. By analyses of the relationship among the velocities, the kinetic energies and the specific kinetic energies of projectiles of different mass at a same firing distance, plus that between the velocities and the specific kinetic energies of projectiles, it was shown that the results are in accordance with the relevant deductions of interior ballistics. The conclusion can be made that “the larger the density of the diameter-same spherical projectile, the higher the specific kinetic energy can be reached at the same shooting distance.” The discovery revealed here may offer some theoretical and experimental supports for regulating the examination of the muzzle specific kinetic energy of BB guns.