The Puckle gun was a primitive autocannon invented in 1718 by James Puckle (1667–1724) a British inventor, lawyer and writer.
The Puckle gun mechanism was essentially a flintlock revolver; the design concept behind the Puckle gun turned out to be years ahead of what was technologically achievable with 18th century technology. The first practical guns using this design principle, now known as revolver cannons, only appeared in the mid-1940s.
Two versions
Puckle demonstrated two versions of the basic design: one, intended for use against Christian enemies, fired conventional round bullets, while the second variant, designed to be used against the Muslim Turks, fired square bullets. The square bullets were considered to be more damaging. They would, according to the patent, convince the Turks of the "benefits of Christian civilization." The square bullets, however, were discontinued due to their unpredictable flight pattern.
Convince the Turks? The Turks would be more keen than anyone on them using the square bullets, they 'd be safe as houses getting shot at
Check out the cylinder on the bottom right