Set two 43-inch boards on edge and parallel. Space them 20 inches apart and set two 20-inch boards between them at right angles, spaced 40 inches apart. Screw through the 43-inch boards and into the ends of the 20-inch boards. Repeat this step so you have two rectangular frames.
Position the two frames upright so they're resting on one of their 43-inch boards, parallel and 24 inches apart. Lay a 31-inch board inside the bottom two corners so the ends of these boards are flush with the outside edges of the frames. Screw through the 20-inch boards and into the 31-inch boards using eight screws for each board.
Lay the pegboard on top of the two frames so one of the 43-inch edges is flush with one of the frames. The frame that it is flush with will be the bottom of the reloading table. Screw the pegboard to the frames in this position using four screws for each frame.
Turn the reloading table frame upright and set your 43-inch plywood on top of the top frame so the edges are flush. Screw the plywood down using eight screws. Set the 36-inch plywood on the lower frame so the edges are flush and screw it to the 43-inch boards using six screws.