A photographic introduction to items from the collection

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The mystery behind teppo (gun) production technology

Seki-School one-kan (3.75 kg) cannon (caliber: 8.5cm, total length: 140cm) Gold inlay in top part of barrel

The introduction of teppo (guns) to Japan is, today, highly evaluated as being the moment of the arrival in our country of a new type of weapon that would greatly influence how battles were fought and of the transfer of advanced Western technology to Japan. Although there is material documenting the change in fighting methods, there are no existing relics, let alone technical information on the teppo from the Sengoku Jidai (the Age of Warring States) to verify the advanced technology supposedly transmitted, which makes this point difficult to comprehend.

It is likely that this argument is based on the preconception that Western culture and civilization are more advanced than those of Japan - a notion that has been around since the Meiji Era - still, some sort of proof is necessary if one were to follow such an argument.

The National Museum of Japanese History houses the collection of Minoru Anzai, the prominent collector of material related to "hojutsu" (gunnery).

This collection includes the "Temaezutsu seisaku no koto" (On the production of temaezutsu), a volume from the "Nakajima-ryu hojutsu kankiroku" (View on the art of gunnery of the Nakajima School) (21 volumes in total), written in May 1843 by Nagataka Munei, a disciple of Atsutoshi Nakagawa of the Suo Tokuyama Clan, and the "Daisho Onteppo Haritate Seisaku" (Making large and small teppo) written by Tobee Kunitomo Ikkansai.

Both volumes are valuable historical material documenting the teppo-making process. In this article, I would like to begin by introducing the contents of the "Temaezutsu seisaku no koto" from the "Nakajima-ryu" series, shown in the illustration, in order to shed some light on the teppo-making technology of the time.

The process of teppo-making

Teppo-making process found in "Temaezutsu seisaku no koto" of the "Nakajima-ryu hojutsu kankiroku"
  1. To make a teppo, one first makes an iron bar called a "shingane". For a teppo one shaku (30.3 cm) in length, the shingane would be one shaku longer, or four shaku. Straw is wrapped lightly around one of the ends of the shingane in order to make it easier to pull out during the teppo-making process.
  2. Next, an iron sheet, called a "kawaragane" is prepared in the appropriate size and thickness to match the teppo. When the kawaragane is ready, it is wrapped around the shingane; the shingane is taken out when the teppo is put on the fire and put back in when the iron is being forged. After the iron has been well forged, the seam is heated until it acquires a paste-like texture and welded together. This is called "wakashizuke". This condition, consisting of a rolled kawaragane, is called an "ara-maki". From this stage, polishing the barrel with a file and attaching the necessary parts will result in a finished teppo. This type of teppo is called a "udon-bari" and is an inexpensive standardized product.
  3. Expensive and well-made teppo are made by joining to the aramaki barrel many sheets of iron, hammered into long strips, wrapping them around the barrel and forging them by wakashi-zuke to make a stronger teppo. The result is called "kazura-maki".
  4. More "kazura" (iron strips; literally, vines) are welded to make a half-molten ara-maki. This is fully melted and welded together, using a hammer to forge the iron from the edge. This is called "tsume-maki". Sometimes, at this point, the cartridge chamber is doubly wrapped. At this stage, the muzzle is wrapped thinly and the breech thickly in a kazura-maki, resulting in an almost complete barrel.
  5. If the entire barrel, and not only the cartridge chamber, is to be doubly wrapped, the strips are wrapped in the opposite direction as the first time. The result is a doubly wrapped barrel.
  6. Next, a thick iron sheet is wrapped around the thinner end (the muzzle) to make the "koji". A rough mold of a pan is made and placed in the cartridge chamber.
  7. The resulting barrel is called an "arakata-zutsu". The arakata-zutsu is put through a hole in a "katagi" (hardwood) and fastened with wedges and the bore is polished using a steel drill. First a rough drill and then, in the final steps, a finer drill is used.
  8. Next, an auger is used to cut a breech bolt hole on the breech.
  9. After one is finished with the auger, a file is used to shape the upper half of the teppo into a round shape, for a round barrel and an octagonal shape for an angular barrel. The shape of the pan is adjusted and the foresight and rear sight are welded on to the teppo by wakashizuke and fastened with breech bolts. Furthermore, a platform for a rivet to be secured to the gunstock is attached to the bottom of the barrel.
  10. Now the teppo is finished. The foresight and rear sights area adjusted next by placing a target on the same level as the bore, normally at a distance of 6 ken (10.9m), and crisscrossing some string in front and behind the barrel, and aiming at the dark spot on the target through the bore. The barrel is then secured; this time one aims at the dark spot on the target through both sights to adjust the sights. This is called the "deai sadame".
  11. After this step, a plank equipped with a mechanism is fitted onto a gun rest made of old hardwood and match clippers and, in the case of an outside mechanism, a spring, as well as a rain-guard, smoke-guard, and trigger are attached to complete the teppo.

Cannon-making procedures

Teppo are small arms but starting around 1570, we begin to see the emergence of large-scale guns with cannons and hand cannons coming into use in the Genki (1570-1573) and Tensho (1573-1592) Eras. The photograph on page 2 shows a Seki-School one-kan (3.75 kg) cannon (caliber: 8.5cm, gun length: 90.2cm, total length: 140cm) donated by firearms historian Sokichi Tokoro with an epigraph reading "Goshu Kunitomo Tanba Daijo Tachibana Munetoshi" and gold inlay on the top of the barrel, which reveals the user to be "Kangun Hyoenojo Masanobu (Seal)". Credible documents attest that the cannon was used to fire over a long distance early in the Edo Period, in 1674, in Kururi, in Kazusa Province.

In August 1813, towards the end of the Tokugawa shogunate, Nobusada Seki, descendent of Masanobu Seki ordered a cannon of 300 me (weight of cannon ball: 1,125g) from Yozo Iwata, an Edo gunsmith. The "Nobusada Memorandum" describes the procedures for making this cannon as follows.

1. A piece of sheet metal is folded in two to make two pieces of 3 shaku (90.9cm) in length, 5 sun (15.15cm) in width, and 8 bu (2.42cm) in thickness a piece. Each piece weighs 5 kanme (18.75kg). The pieces are pressed against a stone with a round dent to shape into half-moon shaped pieces that are joined together to make a cylinder (barrel).
2. The barrel is secured and supported with a ring at the clamp about 3 shaku (90.9cm) in length and a strip about 1 shaku (30.3cm) in length is drawn outside the barrel and is secured by wakashizuke in about three sections from the tip to the middle.
3. Next, iron strips to wrap around the barrel were prepared. Nine strips of 1.1 to 1.2 sun (approx. 3.5cm) in width, 8 to 9 bu (approx. 2.6cm) in thickness, and 4 shaku (121cm) in length were used. The part attached to the barrel had steel pieces of about 5 sun (15.2cm) in length welded on to it by wakashizuke.
4. One person for the tongs, one for the bellows, and four to hammer alternately were positioned near the melting and constantly threw straw and dirt on the barrel. This was to improve the molding. In this way, the barrel with a width of 1 sun (3.03cm) at the upper corner, 3 sun 8 bu (11.5cm) at the sakiguchi, 4 sun (12.12cm) at the honkuchi, and a diameter of 1 sun 5 bu (4.5cm) was produced.
6.Next, came drilling to make a bore in the barrel. A pillar, 2 shaku (60.6cm) from the front where the barrel is put through and 6 to 7 shaku (approx. 197cm) from the side was erected. The barrel was put through the pillar and secured and the bore was made by inserting one after another five aragiri of 5 shaku (152cm) in length with a drill section of 8 sun (24.2cm). At this time, a drill-turner was attached to the drill. The mechanism was that a board to push the drill was set up on the opposite side of the drill and a rope was attached to the board and pulled from the sakiguchi side. A large stone was attached to the end of the rope and when the drill was turned, the board pushed the end of the drill and made a bore.
7.After this, pieces such as fire tongs, platform, and "saruwatari" were forged. Inlay was added to this piece by the engraver Chosaburo Goto.

From the "Hariho-seiho-no-maki" in the "Nakajima-ryu hojutsu kankiroku", one can see that the haritate technology of Yozo Iwata was that of toi-making.

Since Kangun Hyoenojo Masanobu is the eldest son of Shin, the founder of the School and since hojutsu (the art of gunnery) adheres closely to the teachings of the founder, it is possible that the one-kan cannon was also made with this technique. The "Hariho-seiho-no-maki" touches on the techniques of making "udon", "makihari", "kadotoi", and "kanaji" for the cannon base but it is not possible to go into the details in this article.

"Nakajima-ryu hojutsu checklist" & Nakajima-ryu hojutsu kankiroku
"Hariho-seiho-no-maki": Making the udon for the base.
"Hariho-seiho-no-maki": Making the corner toi for the base.
"Hariho-seiho-no-maki": Making the toi for the base.

In the Age of Warring States (Sengoku Jidai), teppo were made by gunsmiths in Kunitomo and Sakai and other eastern provinces of Japan. As can be seen from this fact, smiths all over Japan copied others to make their own iron cylinders. As a result, teppo spread throughout the country. In the teppo-making technology, however, there is no trace to be seen of Western gun-making technology.

Takehisa Udagawa
Japanese Medieval History, History of Arms and Armory Information Reference Research Department, National Museum of Japanese History

Tokoro, Sokichi. "Nakajima-ryu hojutsu kankiroku" ("Edo Koten Kagaku Sosho"). Kowa Shuppan, 1978.
Udagawa, Takehisa. "Teppo to Ishibiya" (Guns and hand cannons) (Nihon no bijutsu). Shibundo, 1997.
Udagawa, Takehisa. "Edo no Hojutsu (The art of gunnery in Edo)". Toyoshorin, 2001.