Transportable shooting backstop

[SuperMagnum]

Building a box and lining it with thick rubber sheet and boards and filling it up is exactly what I was thinking about too. It would have to be plenty thick to stop a 300 win mag tho. I would rather build a huge dirt mound, but my dad wouldn't like that. Maybe i'll just wait till i buy my own place far out in the country and make a range with a dirt backstop.