The 37-mm NS gun was evaluated to estimate the physical and performance characteristics of the 37-mm N gun carried by the MIG-15. The 37-mm NS gun is a belt-fed, percussion-fired, short recoil-operated aircraft gun. The gun operation is describe. The 37-mm N gun does not use the same complete round of ammunition as the NS gun. The N gun was apparently designed after World War II to meet installation requirements for jet fighters. The operation of the N gun may be assumed identical to that of the NS gun.