Japanese muzzle brakes and flash hiders

U.S. Naval Technical Mission to JapanIn 1925 the Japanese Navy developed its first muzzle brake for the 12cm gun. The device was never adopted and the whole idea of muzzle brakes was discarded because: (1) this muzzle brake was unsatisfactory, and (2) muzzle brakes in general were considered unnecessary.
The Navy again studied the problem of muzzle brakes in 1942, when, in order to make the Type 96, 25mm AA gun adaptable for aircraft use, it had to develop a means of reducing the recoil energy. Among other modifications, a muzzle brake, which experimental tests indicated could reduce the recoil energy by 35% was installed. The completed gun, designated Type 4 25mm aircraft machine gun, was never adopted; hence the muzzle brake remained untried in service.
In 1945, the Navy designed a muzzle brake of the simple ring type, in order to permit the use of the 12cm cannon and the 12cm howitzer with the Type 97 Medium tank. The assemblies were the results of a demand for a self- propelled cannon and a self-propelled howitzer. The muzzle brake was considered satisfactory for these assemblies, which, incidentally, never were used in service. Because of the severe blast diverted towards the breech, it was considered absolutely useless for shipboard installation.
The Japanese Navy did not design a satisfactory flash hider. It did adapt the German Rheinmetal design to the Type 96 25mm AA machine gun with fairly satisfactory results, and to the Type 5 (Bofors) 40mm machine gun with unsatisfactory results.