a locking bolt is provided in a mount for receiving a gun barrel or other article . the locking bolt can be cammed relative to the mount from its normally locked position to an unlocked position to permit release of the gun barrel from the mount . the locking bolt is cammed to its unlocked position in response to direct engagement with a key inserted into an interior region of the mount and rotated relative to the mount . thus , the mount is formed to include a keyway configured to permit the key itself to impart motion to a locking bolt to unlock the mount .