Bombards, casting limits, and separate powder chambers

Venetian bombards at Chioggia in 1379 provide an example of stone-firing siege artillery; the larger of two guns is described as throwing an 88.5 kg projectile. Bronze gunfounding drew on bell founders' casting expertise, but at this stage the process limited the size of gun that could be made. Iron's high melting point made consistently cast barrels difficult, while even wall thickness was essential under firing pressure. Wrought-iron rods could instead be clamped with red-hot hoops around a mandrel. That construction left the barrel open at both ends, so a separate powder chamber was wedged or screwed into the breech. The resulting heavy guns took so long to position and lay that siege work suited them better than mobile battlefield operations.