A locking device with a solenoid release actuator includes a housing, a plunger axially slidable within the housing, a biasing member for biasing the plunger in a first direction, one or more locking balls, and the locking balls disposed in an aperture in the housing, the plunger having a portion thereof containing at least one recess for receiving the balls, a member to be locked being held in a first locked position with the plunger in a first locking position and the balls in a radially outward position, the plunger being positioned axially such that the recesses therein are not in alignment with the apertures, and a solenoid coil disposed in the housing around the plunger, for inducing a magnetic force to move the plunger against the biasing member such that the recesses align with the apertures and the balls are movable radially inward into the recesses thereby releasing the locked member. In another embodiment, a bomb, missile or torpedo having a head and tail and fins proximate the tail biased into a retracted position, incorporates such a locking device for maintaining the fins in the retracted position, and for releasing the fins upon solenoid actuation. The locking device may be tested and reset, as desired.