Type Otsu
Kokura Arsenal · Rifle · Prototype · 1932
Also known as: Type B rifle, Japanese Pedersen
Overview
The Type Otsu was a Japanese experimental toggle-delayed blowback self-loading rifle chambered in 6.5x50mm Arisaka. Built in prototype numbers in the early-to-mid 1930s, it was one of a trio of self-loading rifles - Ko, Otsu and Hei - submitted for Imperial Japanese Army trials. Its action was derived from John Pedersen's toggle (hesitation-lock) system, and unlike the American and British Pedersen rifles it fed from a rotary Schoenauer-type spool magazine rather than an en-bloc clip. The Army rejected all of the candidate rifles in 1935, and the Type Otsu never entered mass production.
Specifications
| Action Type | Delayed Blowback |
| Firing Mechanism | Hammer Fired |
| Magazine Capacity | 10 rounds |
| Magazine Type | Rotary |
| Barrel Rifling | Right Hand |
| Frame Material | Steel |
| Barrel Material | Steel |
| Stock Material | Wood |
Calibers
- 6.5x50mm Arisaka · primary — also known as 6.5x50mm SR, 6.5mm Japanese, 6.5x50mm Meiji 30, 6.5x50mmSR Arisaka
Features
- Firing modes: Semi Automatic
- Feed systems: Rotary Magazine
- Features: Toggle Delayed Action, Pedersen Hesitation Lock, Rotary Spool Magazine, Stripper Clip Loading
Service history
Operators
- Imperial Japanese Army
Production
Production years: 1932-1935
Prototype/trials quantity only; rejected after the Imperial Japanese Army self-loading rifle trials of 1935
Origin
Country of origin: Japan
Discontinued: 1935
Notes
The Pedersen (toggle/hesitation-delayed) entry in the Japanese self-loading rifle trials; the rival Type Ko was a Czech ZH-29/Holek-pattern gas-operated design and the Type Hei a domestic gas-operated design. Only a handful of examples were built for testing before the program was abandoned in the mid-1930s.
Background
The Type Otsu ("Type B") took its name from the traditional celestial stems Ko, Otsu and Hei used to number the three rifles in Japan's 1930s self-loading rifle trials; the Japanese never fully grasped the case-lubrication needs of Pedersen's toggle action, so the guns never functioned reliably and the whole program was quietly scrapped.