The 7.7 jap bullets would first be used by the Japanese military in the.303 British cartridge for machine guns installed on early aircraft like the Ro-Go Ko-gata seaplane around the conclusion of World War I. The Imperial Japanese Army sought to produce its own 7.7 jap ammo in various semi-rimmed and rimless cases for the Infantry and the Army Air Service, but the Imperial Japanese Navy continued to equip machine guns with rimmed.303 under the 7.7mm name. In 1919, a 7.7 jap ammo army rifle prototype saw the first testing of a rimless 7.758mm cartridge.  Throughout the 1920s and 1930s, trials would still be conducted, but the development of air-cooled aircraft machine guns would take precedence.
The Imperial Japanese Army started developing a new line of machine guns in 1920, which eventually led to the approval of the Type 89 aviation machine gun versions and the designation of the 7.758mm semi-rimmed ball cartridge in 1930. Lead loaded and 10.5 g in weight, the 7.758mm ball bullet had a cupronickel-plated jacket (162 gr). In addition to being adopted as Type 89 specialty ammunition, tracer, armor-piercing, incendiary, and explosive rounds also received Type 92 designations for air and ground use machine guns in 1934.
Throughout World War II, the Army’s planes would continue to use Type 89 ammo. A bigger projectile was specifically required to improve the terminal ballistics when the Type 92 heavy machine gun was adopted for infantry usage in 1933, hence the 7.758mmSR Type 89 ball cartridge was upgraded to take a 13.2 g (203.7 gr) bullet with a brass jacket. For the heavy machine gun used by the infantry, the ammunition was designated as the Type 92 ball cartridge in 1934.
However, in 1937 it was discovered that rimless cartridges performed better in tests for the magazine-fed Type 97 in-vehicle heavy machine gun. As a result, the Type 92 case rim was reduced from 12.7 to 12.0 mm while keeping the same bullet weight, resulting in the Type 97, 7.758mm rimless cartridge, which was adopted in late 1937. When the Type 99 rifles and light machine guns were being developed in 1940, the Type 97 cartridge’s case was modified because it was determined that a bullet weighing 11.8 g (182 gr) was more effective against short-range targets.
The rim diameter of the Type 97 cartridge was standardized to 12.1 mm with the ultimate adoption of the rimless Type 99 7.7-58mm ball cartridge in 1940, while the late-production Type 92 ammunition was adjusted by decreasing the diameter of the case rim from 12.7 to 12.1 mm to further simplify logistics.
As a result, the older 7.758mm variations, including the specific ammunition, could be used with some accuracy variation in the Type 99 rifles and light machine guns. However, the Type 92 heavy machine gun would continue to use the current semi-rimmed cartridges throughout World War II.
For many years, Norma ammunition has built an outstanding reputation as premium ammunition for hunters in Europe and Africa. Today, Norma USA is pleased to offer American PH, ammunition designed specifically for the North American big game hunter. This ammunition is loaded with premium hunting bullets for maximum terminal performance.
Norma Soft Point bullets are conventional lead-tipped bullets perfect for hunting thin-skinned game. On impact, these bullets rapidly expand and mushroom to produce immediate devastation to the vitals.
WARNING: This product can expose you to Lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to – www.P65Warnings.ca.gov.
Specifications Norma American PH Ammunition 7.7mm Japanese 174 Grain Soft Point