Draw a line across the 4-inch wide side of the 36-inch board. The line is 36 inches long and 1 ¾ inches away from both 36-inch edges of the board. Draw five lines perpendicularly across the first. Start 3 inches from the end of the board, and space the lines 6 inches apart.
Drill a 2-inch hole through each of the intersecting lines. You'll have five evenly spaced 2-inch holes. Erase the other pencil markings.
Draw a 36-inch line across the plywood so it is 3 inches away from and parallel with the 36-inch edges. Draw five intersecting lines across the 36-inch line so they are spaced 6 inches apart and the outside lines are 3 inches away from the 33-inch edges.
Drill a 3/8-inch deep, 1/2-inch hole into each of the intersecting lines on the plywood. Erase the pencil markings when you are finished.
Position a dowel inside each of the holes on the plywood. Screw through the back of the plywood and into each dowel.
Set your 36-inch board on edge and on top of the plywood. The board should be flush with the 36-inch edge on the plywood opposite the side with the dowels. The ends of the board should be flush with the 33-inch edges of the plywood, and the 2-inch holes should be parallel with the 33-inch edges. Screw through the back of the plywood and into the board. Be sure the screws enter the board between the 2-inch holes. Use six screws for this task.
Locate studs in the wall where you want to mount your gun rack. Position your gun rack against the wall and over the studs so the 33-inch edges are parallel with the floor. Use your level to ensure this is true. Screw the rack to the wall so three screws enter each stud. Screw into two studs and space the screws 11 inches apart.
Insert the barrel of your rifles through the 2-inch holes and let the trigger guard rest on the dowels. This rack will hold five rifles.