Zi Mu Chong (子母銃)

UPDATED FEBRUARY 13, 2022, minor update MAY 14, 2023

Ji Xiao Xin Shu (《紀效新書》) variant

Drawing of a Zi Mu Chong and its ammunition, from 'Wu Bei Zhi (《武備志》)'.

Zi Mu Chong (子母銃, lit. 'Mother and child gun'), also known as Zi Mu Pao (子母砲, lit. 'Mother and child cannon'), Zi Mu Fei Pao (子母飛砲, lit. 'Mother and child flying bomb'), and Jing Ying Pao (驚營砲, lit. 'Camp-scaring bomb'), is a type of primitive hand mortar that utilises wooden sabot to reduce windage and propel a grenade at longer distance. Unlike Fei Meng Pao (飛礞砲), a similar weapon, the grenade fuse and the hand mortar have to be lit separately (although it is easily modifiable to use the same firing method as Fei Meng Pao, the reliability is questionable).

The grenade, known as Zi Mu Ping (子母瓶 lit. 'Mother and child bottle'), consists of two primary components: a cast iron casing filled with explosive gunpowder and wrapped in thick paper (also to reduce windage), as well as a wooden rod with a spiral groove carved into it plus a slow match wrapped around the rod following the groove. The grooved wooden rod allows a much longer fuse to be used compared to common black powder grenade, as well as giving some measure of control over the time delay before detonation (i.e. increasing the amount of loops of the spiral groove allows a longer match to be used, thus delaying the detonation). To prevent the slow-burning match from setting off the grenade prematurely, the wooden rod is also wrapped in thick paper.

Zi Mu Chong is a potent ambush and night raid weapon due to its time-delayed grenade (making it difficult to determine the direction the attack is coming from), not to mention the grenade produces very little smoke and is difficult to disarm since most of the fuse is embedded inside the casing.

This weapon should not be confused with another breech-loading matchlock gun of the same name, nor with Qing period name for breech-loading cannon.

Cheng Shu (《城書》) variant

Top left: Pomegranate-shaped grenade. Top right: Standard can-shaped grenade. Mid: Zi Mu Pao with lengthened barrel. Bottom: Zi Mu Pao mounted on a rest. From 'Cheng Shu (《城書》)'. 

Late Ming period siege defence treatise Cheng Shu (《城書》) recorded a different variant of Zi Mu Pao with longer barrel and a gun rest. It also introduced a new grenade, know as Tie Shi Liu (鐵石榴, lit. 'Iron pomegranate', most likely a type of iron fragmentation grenade), as an alternative to existing can-shaped grenade.

The author of Cheng Shu also suggested to load the grenade fuse-first into the barrel to simplify the shooting process (as ignition of powder charge inside the gun barrel will also ignite the grenade fuse), which seems to suggest that sabot was no longer used.

Top left: Casing of Zi Mu Ping grenade. Top right: Paper-wrapped wooden rod with fuse, separated from the casing. Bottom: Gun rest for Zi Mu Pao. From 'Cheng Shu (《城書》)'.