Comparative Analysis of Different Methods of Calculating Pressure Inside the Barrel in Post-Muzzle Period of a Shot

The article presents the results of calculations of the pressure of propellant gases inside the barrel in a post-muzzle period of a shot. Three methods of calculating the pressure in the barrel bore in the post-muzzle period of the shot were used in the work: the Brawin method, the method describing the outflow of gases from the barrel bore to the environment, and the method using the phenomenon of the transition of a pressure-averaging rarefaction wave from the barrel muzzle to the bottom of the combustion chamber. In the conducted tests, the obtained pressure courses were used to determine the impact of the use of various methods describing the post-muzzle period of a shot on the behaviour of the weapon automatics system operating on the recoil principle. A comparison of the pressure courses, obtained with the use of various methods, and the recoil velocities of the elements of the recoiling assembly, determined with the use of mathematical and physical models of recoil firearm operation, showed that in the case of recoil operated weapons, the differences between the methods are small - the differences between the recoil velocities determined with the use of various methods did not exceed 5%. Both, the pressure courses and the recoil velocities of the recoiling elements of the firearm operating on the recoil principle determined with the use of various methods of describing the pressure course in the post-muzzle period of the shot are at a similar level.