I live on 5 acres. My house is pretty close to dead center on the property. I have a 30' x 40' pole barn to one side of the property. I've been thinking about building a pistol range inside the barn. I would probably use railroad ties to construct an 8' x 8' backstop, likely in a semi U shape. A couple layers of 3/4" plywood and backed with 1/8" sheet steel. A furnace blower / exhaust fan to vent the gases. I'd love to hear thoughts, comments, etc.