You don't have 13 acre, you have 572 acres. You need to find a way to bring them to your 13. FOOD AND PRIVACY.
But you have to build a shooting range.
CONGRATULATIONS HAVE FUN. 👍
Sounds good, for the concrete put pipe sleeves were you can bring your wires or whatever. You can get fire caulking to put in after your done. It's removable if needed. 👍
Mine is 4×4 legs, 2×6 framing on 12" center, 3/4 cabinet grade plywood with 3/16 stainless steel 12" wide top where anything is mounted, all glued, screwed and bolted. Build it as strong as you can. 👍
Legs are bolted down also.