Locate a wall space that is open and where hanging a large picture would seem reasonable. It is better if it is in a room that is not heavily used, such as a den, home office or master bedroom.
Test the space available by placing a large wall hanging on the proposed location. Coverage must be at least 6 inches wider than the safe on all sides. Mark the location of the corners of the wall hanging with a pencil, then remove the wall hanging.
Find the center-most wall studs that fall between the edges of the wall hanging. Adjust the position of where the wall hanging will go if necessary to have the studs centrally located. Make sure the security box fits in between the studs.
Hold the box up to the wall where it will go and outline it with a pencil. Add a 2-inch margin to the top and bottom of the cabinet space.
Keyhole or rotary saw around the pencil marks to remove the drywall section.
Create a frame for the safe by securing a 2-by-4-inch horizontal beam at the bottom of the hole with the L brackets and screws. Place the safe on top of the bottom beam and pencil in where the top beam goes for a snug fit. Remove the box and use the L brackets to attach the top beam.
Place the safe into the frame against one side or the other. Screw wood screws into the 2-by-4s through the interior top, bottom and side holes.
Seal the exposed drywall with tape and mud so that no dust escapes to reveal the safe location. Paint over the edges if you desire a finished look to the project.
Install the guns in the safe and place the wall hanging over the safe.