Gun dynamics

Gun dynamics describes the physical causes of barrel and shot vibration, and the effect they may have on accuracy and consistency. It is employed to predict firearm performance, such as recoil, using theoretical methods and mathematical modelling techniques. In the 1970s, the United States Army Symposium on Gun Dynamics defined it as the study of internal ballistics that are unrelated to propellants and combustion. In particular, it is concerned with the interactive dynamics between the projectile, barrel, and mounting, and the effect that they have on the accuracy and consistency of the gun.

Gun designers realized that there may be an interaction between the barrel and the shot that was likely to affect accuracy and consistency. It is only since the 1970s that the ability to compute the motion has become practical. If a perfectly straight barrel was fired in zero gravity, the barrel recoiled along its central axis with no off axis forces, the shot was perfectly balanced and a perfect fit within the barrel, and all the forces were symmetrical, then the shot should exit the barrel in the direction in which the barrel was initially pointing. In practice none of these conditions can be met, and inevitably, some transverse vibration is introduced to the barrel and the shot. This results in shot jump, where the trajectory does not correspond with the initial direction of the muzzle.