Peg board is good but depending on thickness there is a chance, over time, that a heavier gun could pull the hanger down and break the peg board.
Slat board (slotted from end to end) is a little stronger, but more expensive. There are two types, one with just the mdf and the other has a metal strip through each slot. The board and hangers and much more expensive then peg board.
If you decide to go with peg board, use 1x2s and anchor into the studs behind the drywall. Butterfly anchors have a chance to pull through the drywall if there is too much weight on them. You'd want the board to be anchored to structure as opposed to finish material. If you decide slat board then you can anchor that directly to the wall. When you anchor, find the stud spacing, and either screw through the face of the board or through the slot, depending on how you want it to look.
Make sure to use screws that fasten at least 2/3 of the screw length into the stud behind.
If you plan on painting it, make sure to give it a light sanding so the paint adheres to the board.
Hope this helps!
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