An apparatus for correcting trajectories variations of projectiles launched from a firearm is disclosed. The apparatus includes a control circuit for determining an appropriate impulse to be imparted into a projectile based on the measured velocity of the projectile, at least one steering coil, and a pulsed-power supply for discharging an amount of energy commensurate with the determined impulse to the steering coil such that a set of magnetic fields is produced to impart an amount of corrective kinetic energy into the projectile as the projectile passes the steering coil.

A projectile including: a body having an internal space; and a mechanical stepper motor disposed in the body, the mechanical stepper motor including: a shuttle having one of a plurality of pockets and movable pins offset from each other with a first spacing; a body portion having the other of the plurality of pockets and movable pins offset from each other with a second spacing, where the first spacing is different from the second spacing; and actuation means for engaging at least one of the movable pins into a corresponding pocket to step one of the shuttle and body portion a predetermined linear and/or rotary displacement; wherein the mechanical stepper motor outputs the predetermined linear and/or rotary displacement to an actuated device operatively connected to the shuttle.

A guidance unit system is configured to be used for a ground-launched projectile. The system includes a housing configured to be attached to a ground-launched projectile. The housing is coupled to an attachment region that attaches to the projectile, wherein the housing is configure to rotate relative to the attachment region. A motor is contained within the housing and a bearing surrounding the motor. The bearing is rigidly attached to the housing such that the motor rotates with the housing and shields the motor from inertial loads experienced by the housing.

A system can include a spinning structure configured to spin in operation, and at least one mass operatively connected to spinning structure to rotate about a spin axis with the spinning structure. The at least one mass can be configured to be moved relative to the spinning structure during a spin of the spinning structure. The system can include an actuation system configured to move the at least one mass relative to the spinning structure. The actuation system can be configured to move the at least one mass while the spinning structure is spinning to use the spin of the spinning structure to induce a precession torque on the spinning structure. The actuation system can be configured to synchronize actuation motion of the at least one mass to the spin of the spinning structure such that the induced precession torque is in a desired direction.