15th Century Continuation 2 1461: First mention of a flash pan lid in writings from Nürnberg. 1464: Possibly the largest cannon with a bronze barrel length of 5 meters, a caliber of 66 mm and a weight of 18 ¾ tones. The so called Dardanellen artillery was made at the siege of Constantinople in front of the city’s walls, by Mohamed the II the Turk. 13 cannons were successfully used for the siege. One of them split. The powder chamber could be threaded off and had a thread diameter of approximately 60cm. Weight of the balls 720 pound. Ca. 1490: Leonardo Da Vinci draws plans for a wheel lock with a coil spring and a friction rod lock. It is not clear if this mechanism was a tool to light fires or if it was a lock for firearms. Ca. 1490: Introduction of the hammer spring with button release on match-locks. Ca. 1490 First use of the breech plug with external thread to close the barrel at the breech.