An electromagnetic lock assembly has longitudinally extending interlocking protrusions and recesses in the magnet and magnet housing surfaces. This permits longitudinal movement of the magnet within the housing, but prevents lifting of the magnet out of the housing. End caps and an electronic circuitry cover clamp the magnet longitudinally within the housing and provide the mounting bolt brackets. An armature, providing for distribution of separating forces, reduces bending tendencies in the armature contact plate and thereby increases the effective separation load bearing capability of the lock assembly.