A sliding trigger enclosure system for a long gun includes a frame that is removably secured to the receiver of a firearm by factory-supplied hardware, and a hollow shoulder stock having a pair of side surfaces that extend outward from the front end. The shoulder stock is slidingly engaged over the frame and transitions between a FIRE position where the trigger assembly of the long gun is accessible, and a SAFE position where the pair of side surfaces are locked in a parallel orientation to the trigger assembly to prevent access to the same. A locking mechanism is disposed along the frame and secures the shoulder stock in the SAFE position. The locking mechanism including a pair of spring-loaded locking pins that are engaged by an actuator, and a user authentication device.