Splitting this off from Darren's "list thread"...
Sandy - You suggested a perspex seperator?
Nah man, would cost hundreds if not thousands!
I think the best way to lay out the range would be to get hold of a roll of thin mesh scaffold netting, and use that as a side wall, if we want to do anything other than block off an entire room / corridor!
A simple white sheet a foot or so out from the wall will be an effective backstop, pegged or sewn up to form a bag at the bottom to collect stray BBs ( Which we will NOT be re-using!

).
Another point to consider will be the targets - the Nerf targets were laminated and knocked over.
Do we just want to go with the same thing here? If so, I can build a wee rig with hinged clamps for the targets to sit in. Just lemme know.