I found this stuff on line but I can't find any reviews. Anybody familiar with it?
Backstop Netting (http://www.westcoastnetting.com/netting-products/sports/archery/knotted-woven-mesh-fabric.html)
I know they use a large netting similar to the one described to protect the walls at school for the school archery programs. Those bows are the 20 pound ones though.