8mm Nambu

8×22mm Nambu
Japanese military cartridge.
Type	Pistol Submachine gun
Place of origin	Japan
Service history
In service	1904–1945
Used by	Japan
Wars	Second Sino-Japanese War World War II
Production history
Designer	Kijiro Nambu
Designed	1902
Specifications
Case type	Bottleneck rimless
Bullet diameter	8.13 mm (0.320 in)
Neck diameter	8.71 mm (0.343 in)
Shoulder diameter	10.00 mm (0.394 in)
Base diameter	10.23 mm (0.403 in)
Rim diameter	10.50 mm (0.413 in)
Rim thickness	0.92 mm (0.036 in)
Case length	21.43 mm (0.844 in)
Overall length	31.56 mm (1.243 in)
Primer type	small pistol
Ballistic performance
Bullet mass/type Velocity Energy 102 gr (7 g) FMJ 290 m/s (950 ft/s) 274 J (202 ft·lbf)
Test barrel length: 117 mm (4.61 in)

The 8×22mm Nambu is a rimless, bottleneck handgun cartridge introduced in Japan in 1904. It was used in the Type A and B Nambus, Type 14 Nambu and Type 94 pistols, Tokyo Arsenal Model 1927, Type II machine pistol, Hino Komuro M1908 Pistol and the Type 100 submachine gun. It uses 8.2 mm (.320") bullets. Power is relatively low, with military loads developing about 280 J (200 foot·pounds), comparable to the American .380 ACP and substantially weaker than contemporary military cartridges such as 9×19mm Parabellum, .45 ACP, and 7.62×25mm Tokarev.

As per the fate of almost all contemporary Imperial Japanese weapon designs, the 8 mm Nambu production ceased after the end of World War II, as the weapons that fired it were removed from service. While some small-scale production (primarily using remanufactured brass) has occurred in the United States, handloading is common among owners of 8 mm Nambu pistols. New manufactured brass and copper plated lead bullets (.320") are now available through HDS.

The Japanese Army cartridges in 8 mm Nambu have no markings on the headstamp unlike the Japanese Navy cartridges.