Zi Mu Chong (子母銃)

UPDATED FEBRUARY 13, 2022, minor update DECEMBER 29, 2023

Ji Xiao Xin Shu (《紀效新書》) variant

Drawing of a Zi Mu Chong and its iron canister grenade, 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'), was a type of early hand mortar. Unlike Fei Meng Pao (飛礞砲), a closely related weapon, Zi Mu Pao utilised wooden sabot to reduce windage and to propel the grenade at longer distance, and its grenade had to be lit separately from the hand mortar (although it was easily modifiable to use the same firing method as Fei Meng Pao, the reliability was questionable).

Zi Mu Chong's grenade, known as Zi Mu Ping (子母瓶 lit. 'Mother and child bottle'), consisted of two primary components: a cast iron canister filled with explosive gunpowder and wrapped in thick paper to reduce windage, as well as a wooden fuse identical to that of Du Huo Fei Pao (毒火飛砲), which was a burning fuse winded along the threads of a screw-threaded wooden rod. The threads on the wooden rod allowed a much longer fuse to be packed into a relatively small space, as well as giving some measure of control over time delay before detonation. To prevent the burning fuse from setting off the grenade prematurely, the wooden rod was also sealed inside a thick paper tube.

Zi Mu Chong was a potent ambush and night raid weapon due to its time-delayed grenade (making it difficult to determine where the attack came from), not to mention the grenade produced very little smoke and was difficult to disarm as most of the fuse was 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》)'. 

A different version of Zi Mu Pao with longer barrel and a gun rest is recorded in a late Ming period siege defence treatise called Cheng Shu (《城書》), which also introduced a new ball grenade know as Tie Shi Liu (鐵石榴, lit. 'Iron pomegranate'), as an alternative to existing can-shaped grenade.

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》)'.

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 would also ignite the grenade fuse), although this implies that sabot was no longer used.