By the early 1800s gun-founders knew that two metals were suitable for the manufacture of cannon, iron and bronze. Bronze, an alloy made up of about 90% copper and 10% tin, was strong enough to resist the explosion of gunpowder without bursting the cannon. The guns were often referred to as brass cannons when in fact their composition was of bronze. The weakness of bronze guns was that, if fired too rapidly, they overheated and warped. Iron cannons were much cheaper to manufacture and they did not warp from overheating. However, cast iron was more brittle than bronze. Iron cannons were heavier that bronze guns; this was not a problem with large caliber weapons aboard ships or in fortresses, but field artillery needed to be lighter and more mobile.
