You might take an interest in the following two links:The Guns of ConstantinopleArtillery Trade of the Ottoman Empire
In 1453, the first significant and decisive use of cannons occurred at the Siege of Constantinople, the greatest of all medieval fortresses, with 13 miles of city walls.
Called the "Precursor of Antichrist" by Christians because he was allegedly a sadist, a bisexual, and a sodomite, Sultan Mohammed II of the Ottoman Turks laid siege to Constantinople in April, 1453. He brought with him 68 Hungarian-made cannons, the largest of which was a gigantic 26-ft-long gun that weighed 20 tonnes, fired a 1,200-lb stone cannonball, and required an operating crew of 200 men.
For 50 days, the Turkish cannons bombarded Constantinople and ripped holes in its walls, but each time the Turks charged into the gaps, the defenders repulsed them and hastily rebuilt the walls. Finally, on May 29, 1453, a destructive cannonade toppled a wide stretch of the walls, and 12,000 elite Turkish troops successfully rampaged into the city.