[DeeDubya]

My son's coming down for Formula 1 this weekend and we're hoping to find some spare time to test this thing. I'm planning to first shoot 22 rifle and check penetration. If all looks good then on up to 265gr 45 win mag out of a 14" Contender. That should move some sand. My hopes are that the sand will splash up and back and then flow back down to fill the void. If the sand is dry and loose it should be self-maintaining. Also, there might be a better choice than the asphalt board. There are new types of insulation board (like the blue poly foam) but I don't know if staples will hold in it. We'll have to experiment.