rufus; It sounds like you are building a backstop for a firing range, you should check with the CFO, (anonymously of course) the requirements for such a range. If it is just for personal use on you own property there may not be too much a problem. However, the rules are open to interpretation and that of the new sherriff in our town requires us to spend another $2000 on ranges we have already spent $10,000 on in upgrades to bring it to military specs, but this is a club. But a friend of mine also had the range on his own property inspected, and it also needed upgrades. He is a dealer though and test fires everything up to and including automatic rifles so that may make a difference. But considering Mr. Doofus, this is not a case where it is easier to ask forgiveness than permission if he happens to complain, you could put a lot of effort into something the CFO will not allow you to use. Just a thought, but like I said, ask the questions candidly, the CFO is full of gun grabbers too.