Particularly in England and France during the Hundred Years War
But also by the Mongols and the Yuan, and the Majapahit Empire (which i just found out about on wikipedia :) )
The two common technologies in Europe were casting in bronze, and forged from wrought iron. The wrought iron guns were typically made from strips of iron running along the length of the barrel being welded together, which would form the inside of the barrel. This was then reinforced by iron hoops heat shrunk onto the outside to stop the barrel from splitting along the welded seams. These reinforcing bands could form either a complete layer:
or be discrete separate bands:
https://commons.wikimedia.org/wiki/File:Bombarda_Museu_Marinha_Lisboa_1.jpg
https://commons.wikimedia.org/wiki/File:40KgWroughtIronMurderer1410France.jpg
The inner strips running along the barrel and the reinforcing bands can be seen clearly in this falling-apart example:
To these, we can add that the Chinese were also casting guns in cast iron in large numbers already in the 14th century. One interesting variant was the forging of the inner barrel, followed by the casting of a reinforcing layer of cast iron around it.
The bronze guns are straightforward, although large ones presented technical problems due to their size. Some examples:
14th century European: https://commons.wikimedia.org/wiki/File:Tannenbergb%C3%BCchse.jpg
14th century Chinese: https://commons.wikimedia.org/wiki/File:Bronze_cannon_of_1332.jpg
16th century Ottoman: https://commons.wikimedia.org/wiki/File:Turkish_Bronze_Cannon.001_-_Tower_of_London.JPG
Very early barrels in China might be made of paper or bamboo, reinforced by being wrapped by wire or cord. These were typically for fire-lances, the gunpowder flame-thrower ancestor of the gun, but were also used for guns (and fire-lances that also shot projectiles). Wooden barrels were also used for fire-lances in Europe (presumably reinforced like the Chinese examples). Iron-reinforced and iron-lined barrels were occasionally used for cannons, with some being relatively recent:
A cheap and nasty alternative to all-metal barrels!
