In order to meet the special requirements of the feeding system of the high firing rate automatic gun of a small bore, a scheme of the cross helix chainless feeding system was proposed, which could realize the orderly recovery of cartridge cases. The 3D model of the cross screw chainless ammunition feeding device was established, and the virtual prototype model of the chainless ammunition feeding device was established by using the multi-body dynamics simulation software. The movement rules of the feeding, handover and cartridge case recovery were simulated and analyzed under the condition of 4 000 rounds/min RF. The simulation results show that the axial velocity is 0 and the axial displacement is constant when the 28 projectiles are handed over, the process of feeding handover and cartridge case recovery is smooth, and the structure of the feeding system is reliable and reasonable. The scheme meets the design requirements of a certain type of automatic gun, and can provide a reference for the development of related chainless feeding system.