Abstract: Locking device for securing a firearm to a wall, having a first part securable to the wall and a second part insertable through the trigger guard of the firearm to be engaged with the first part, the second part being so shaped as to then retain the firearm on the wall. The second part has a shank portion which enters into an opening in the first part and a lock is provided operable to hold the shank when so entered. The first part is securable to the wall by screws passing through screw holes in the first part, which screw holes are selectively exposable by rotating a cover plate on the first part to align an opening in the cover plate with the screw holes. When the second part is locked to the first part the shank passes through the cover opening into the second part to lock the cover against rotation so that it cannot be rotated to a position giving access to the screw holes.