OK, based on Boyntonstu's latest very interesting threads, I looked at improving my "toilet brush" ammo a bit. The nine inch nail tips worked very good, but all penetration ended at the plastic handle of the brush. So I made a new "arrow", from a 12 mm steel tube (1mm walls). The tip is massive steel, and the "hooks" are made from flat steel, sharpened towards the front and rounded at the back. The loop for the sear is recessed into the tube. This offers no resistance to tissue once the tip is in. I tested it against the "Dragon scale", and - believe it or not - it tickled the Dragon. The 330 gram arrow crashed through the stainless steel plate and through the half inch quality plywood. Not bad! Of course this isn't as effective as the Smaug ballista - but it has a fraction of the draw weight and only 2 meters of a barrel length.