you might try this i was target shooting my .223 ar 15 kind of the same set up i took a piece of wall board the kind with the holes in it for a shop or garge but any thin plywood would work and made two legs that you could fold out like a table leg and it worked great but remember if your are on pulic property by a dam it might be illegel to shoot there also i lived in ky and there they had public shooting ranges in the state and us gov fish and wildlife area and we do here in indiana aswell were i live now