ulfrik, I don't mean suggest that all tubes are inherently weak or inaccurate - I just think the commercial store-bought (yellow Daisy's I have) have chosen longevity over performance and the inaccuracies probably comes from holding a heavier draw at maximum extension (using a consistent anchor point). Compared to Theraband Gold flats, it feels like the difference between shooting a 75 # recurve bow to a 75 # compound bow.
There's no free lunch however, and I'm pretty certain the Daisy bands will last 5x the number of shots as the Therabands. There are also much lighter/faster tubes you can buy on the dedicated slingshot sites, but they won't last as long either.
Pete, agree lead is probably the best hunting ammo, most kinetic energy for a given wind resistance, less ricochet risk, but more handling/environmental health concerns, and "vacuuming" steel at the bottom of your target catchbox with a magnet sure is nice. Steel sells for $3.50 a lbs, any size.
Very cool idea Hangfire, especially like the sights which I think these things really could use.