Del, I don't have any 4831 or 160rn, but will probably use 160 or 140 bthp, and 4064.
Dusty, I think I have some quickcrete, from my shed project last month, but I won't arrive until Friday, so there might not be enough tome for it to harden. Using cement cans for projectiles, you could put a loop of heavy wire in the end, and attach a streamer that way, make them easier to find and re-use. Just be sure not to hit Jerry's long range target frame, I don't know if it's rated for artillery use.....