Chongtong

From 1356 onwards, Korea was much harassed by wokou, and the king of Goryeo, Kongmin Wang, sent an envoy to the court of Ming China appealing for a supply of firearms.

Although China at that time was under Yuan dynasty, the first Ming leader, the Hongwu Emperor, seems to have treated the request kindly and responded in some measure.

The Goryeosa mentions a certain type of bombard, the chongtong, which could send arrows from the Nam-kang hill to the south of the Sun-ch’on Sa temple with such force and velocity that they would penetrate completely into the ground together with their fins.

[2]: 307  A royal inspection of a new fleet happened in 1373 including tests of guns with larger barrels for shooting incendiary arrows against the pirate ships.

In the following year, another request was made to the Ming emperor after the military camps at Happo were set ablaze by wokou, with over 5000 casualties.

In 1596, more improvements were made, and by this time (i.e., on the dawn of the Imjin War), the Seungja class of hand cannons were phased out in favor of Japanese-style muskets and arquebuses.

The 'Black' (현자총통; 玄字銃筒) type was about 0.8 m (2 ft 7 in) long with a bore of about 8 cm (3.1 in) and could fire a 'chadajeon' (similar to the janggunjeon) that weighed about 3.5 kg (7.7 lb) up to about 1 to 2 km (0.62 to 1.24 mi).