When I did mine I had an operator with his no-kidding bulldozer come in and push up a 10’ Tall x 36’ wide berm from scratch. Took him about 2.5 hrs, I think total cost was about $300. Worth every cent. I had him cut the front face vertical and I built a 10’ Wood retaining wall. About another $500. I’ve used it more than 20 years now never regretted the initial cost - it’s turned out to be a great investment. Wall has to be repaired now and then bu it’s no problem. Whatever you do, be sure there is nothing beyond it at least as far as a bullet can travel, and fanning out from your shooting position.