Volley gun
The Ribauldequin was a medieval version of the volley gun. It had its barrels set up in parallel. This early version was first employed during the Hundred Years' War by the army of Edward III of England, in 1339. Later on, the late Swiss army employed it.
Naval artillery in the Age of Sail
The Paixhans gun (French: "Canon Paixhans") was the first naval gun using explosive shells. It was developed by French general Henri-Joseph Paixhans in 1822–1823 by combining the flat trajectory of a gun with an explosive shell that could rip apart and set on fire the bulkheads of enemy warships. The Paixhans gun ultimately doomed the wooden sailship, and forced the introduction of the ironclad after the Battle of Sinop in 1853.
In addition to varying shot weights, different types of shot were employed for various situations: