Thanks. From your article:
" While the detachable air reservoir was capable of around 30 shots it took nearly 1,500 strokes of a hand pump to fill those reservoirs. Later, a wagon-mounted pump was provided. The reservoirs, made from hammered sheet iron held together with rivets and sealed by brazing, proved very difficult to manufacture using the techniques of the period and were always in short supply."
Hardly a weapon that could be handily used in a modern school or public venue massacre, is it? It wouldn't even work well in ancient times battle, unless the operator had a *lot* of covering fire while he pumped it up.
I repeat -- the framers of the 2nd Amendment did not foresee the advance of weaponry to the stage that it is now.