One of the key technologies of stacked projectile weapons is projectile positioning. However, the present projectile positioning structures have their respective advantages and shortcomings. A new structure based on the self-locking principle is put forward in this paper and verified as feasible by static analysis if the proper material and structural parameters are chosen. In order to check the strength and verify the feasibility of the structure under launch conditions, the multibody contact finite element model of the structure is established, coupled with dynamic load in the interior ballistic cycle. According to simulations and analysis, the projectile positioning structure is feasible and the strength of the projectile can meet the strength requirement for launch conditions. For different maximum static friction coefficients, simulations show that an increase in the maximum static friction coefficient between the contact surfaces of the positioning ring and barrel improves the positioning performance, but an increase in the maximum static friction coefficient between the contact surfaces of the positioning ring and projectile worsens. On the basis of great computation, it is found that an increase in the upper thickness and height of the positioning ring improves the positioning performance, but an increase in the lower thickness worsens the positioning performance. Further, a lower thickness affects the positioning performance more greatly. As a result, the positioning ring will be thin and light to improve the positioning performance. Compared with other positioning structures, the new structure has little influence on the ballistic performance and is a good application prospect.