Abstract: During the muzzle-exit phase, the centrifugal inertial force generated at the maximum spin rate of the projectile drives the centrifugal block in the inertial firing mechanism to compress the spring and remove the restriction on the moving component, thus completing centrifugal arming release and ensuring reliable firing of the projectile. To obtain the rotational-speed range required for centrifugal arming release of the projectile in the muzzle-exit stage and guarantee subsequent successful firing, this paper takes the M739-type reproduced projectile as an example. Firstly, the operating principle of the centrifugal safety device inside the inertial firing mechanism is analyzed; secondly, a force analysis is performed on the centrifugal block of the firing mechanism, the centrifugal arming-release condition for the muzzle-exit phase is established, and the initial-condition parameters are substituted to calculate the minimum rotational-speed for arming release; finally, the centrifugal safety device at the instant of muzzle exit is simulated by the dynamics-analysis software ADAMS, so as to verify the correctness of the arming-release condition and the rotational-speed range.