Place of origin
World War II
Type B Nambu Pistol 1. Tokyo Artillery Arsenal, Koishigawa, Tokyo 1903-1923 and 2. Tokyo Gas and Electric Co., Ltd., Tokyo 1923-1929. Was ammunition made in the same factories?
No. built Pistols - Possibly less than 6,500. 1. Tokyo c. 5,900 and 2. TGE c. 550. Number of 7x20mm rounds made is unknown but today they are a quite rare collector's item occasionally found in WW2 boxes of 50 rounds.
At least 5, including a dummy. Variations mainly occur in type of bullet crimping, jacket type and rim thickness.
Bullet diameter 7.08 mm (0.279 in)
7.64 mm (0.301 in)
8.62 mm (0.339 in)
8.91 mm (0.351 in)
9.11 mm (0.359 in)
0.98 mm (0.039 in)
19.80 mm (0.780 in)
26.80 mm (1.055 in)
Primer type Small pistol
56 gr (4 g)
FMJ 240 m/s (790 ft/s)
108 J (80 ft·lbf)
Test barrel length: 83 mm (3.25 in)
7×20mm Nambu is a rimless, bottleneck handgun cartridge designed in Japan for use in the Type B or "Baby" model Nambu pistol. The cartridge is a scaled-down version of the  8×22mm Nambu used in all other Nambu pistol models. It has a muzzle energy more than a .25 ACP and close to the .32 ACP.   
References [ edit ]
^ Miller, David (2007). Fighting Men of World War II, Volume I: Axis Forces—Uniforms, Equipment, and Weapons. Stackpole Books. p. 276. ISBN 0-8117-0277-4.
^ "An Introduction to the Military Handguns of Imperial Japan". Gun Digest 2010. Krause Publications. 2009.
^ Dave Maccar (2016). Handguns & Handgun Shooting. p. 88. ISBN 1440246106.
^ T J Mullin (2015). 365 Guns You Must Shoot: The Most Sublime, Weird, and Outrageous Guns Ever. p. 167.
the Hand Cannons of Imperial Japan, Derby,H., 1981, Taylor Publishing Company, ISBN 0-940424-00-2 The Weapons Series no. 5 THE BABY NAMBU Japanese 7-mm. Pistol. Marsh, Roger, 1946, Pub. by the author.