The Hino-Komuro pistol (sometimes spelled Komura) was developed by a young Japanese inventor named Kumazo Hino, and financed by Tomijiro Komuro in the first decade of the 20th century. The gun uses a virtually unique blow-forward mechanism, which makes it very interesting to study. The rear of the receiver houses a fixed firing pin, and the barrel is pushed forward upon firing. To cock the gun, the barrel is manually pulled for ward about one inch (using serrations on the exposed front section of the barrel). As the barrel is pulled forward, it pulls with it a follower that pulls a cartridge forward out of the magazine and lifts it up into the axis of the bore. When the grip safety and trigger are depressed, the barrel is snapped backwards into the action by a spring. The ready cartridge is chambered and driver backwards with the barrel onto the fixed firing pin.

The design has no locking mechanism, and it is just inertia of the barrel traveling backwards that holds everything together until the bullet leaves the muzzle (as with any blowback design). The recoil energy from the shot has no way to push the breech of the gun rearwards, and so instead it acts on the barrel, pushing it forward against the recoil spring until it locks in place, ready for the next shot.

There are only about a half dozen known examples of the Hino-Komuro still existing, and most are in .32ACP caliber, with a couple in 8mm Nambu. Period advertising for the gun indicates that they were offered in other calibers as well (including 5mm and 6.35mm), although it is not known how many (if any) were made for other cartridges. It is believed that about 1200 guns were made in total between 1908 and 1912.

Videos

Photos

We had the opportunity to handle this Hino-Komuro in .32ACP (click here to download in high res):

.32ACP Hino-Komuro magazine (click here to download in high res):

Patents

US Patent #886,211 (K. Hino & T. Komuro, Pistol, April 28, 1908)