On 15th May 1718 he took out a patent for the weapon, which was fired by flintlock. It was mounted on a tripod (making it portable), and could have various six-chambered breeches attached so that it could fire round bullets at Christian targets, and – for some reason – square bullets at Turks. The firer rotated a the breech with a handle, very much like the later Gatling Gun.
Like so many inventions that arrived before their time, Puckle’s Defence Gun was lampooned and failed to attract investment, even though it was successfully demonstrated. According to the London Journal of 31st March 1722, ‘one man discharged it 63 times in seven minutes’ in the pouring rain. The second duke of Montagu took two of the machine-guns to St. Lucia during his failed attempt to take control of the island.
If you wish to learn more about the Defender Gun, the Wedmore family history web site has a page with details of the patent , and the Royal Armouries museum in Leeds has an example of the machine-gun in its collection.