Largest known wrought-iron bombard by caliber - photo

[Frank S]

What amazes me is how they moved this very heavy gun to the battlefield.

As far as bombards go used as heavy artillery pieces this one was comparatively lightweight.
Being made from strips of wrought iron wrapped stacked and folded back on each other in a few layers gave it slightly superior strength than a cannon cast of bronze or iron per a given weight.
this Pumhart von Steyr bombard was around 2.5 meters long and weighed 8 tons.
https://en.wikipedia.org/wiki/Pumhart_von_Steyr
To be sure there were much larger and heavier long cannons and short cannons or Mortars,cast from iron or bronze though
https://en.wikipedia.org/wiki/Tsar_Cannon
THe Steyr wrought iron bombard would fall in the classification as a mortar due to its short barrel length to bore ratio