If opportunity presents itself in East OK area, I'm considering purchasing some land to build a private shooting range. Looking for suggestions for acreages - how deep should the range to shoot safely? I mostly shoot AR-15 55 grains and 9mm from various glocks. Occassionally .22LR from a handgun. What's the safe height and width for a backstop? Dirt? Sand? Which material is better for a backstop? Thank you for any suggestions / ideas / recommendations.