Major developments: Large-calibre artillery weighing several thousand kg are produced in Europe during the early 15th century and spread to the Ottoman Empire. Modifiable two wheeled gun carts known as limbers and caissons appear, greatly improving the mobility of artillery. The matchlock arquebus, the first firearm with a trigger mechanism, appears in Europe by 1475. Rifled barrels also appear in the late 15th century. The term musket is used for the first time in 1499. Rocket launchers are used in battle by the Ming dynasty and the Korean kingdom of Joseon develops a mobile rocket launcher vehicle called the hwacha. Chinese style bombs are used in Japan by 1468 at the latest.