We recently had the opportunity to take a look at a 1908 Japanese Hino-Komuro pistol – one of the most unique guns we’ve yet seen. It’s one of the very few true blow-forward designs ever built, and very few are known to still exist.
Over on the Hino-Komuro page of the Vault, we have photos of the gun and a copy of the US patent on the design (including several cutaway drawings). This pistol is so cool I can barely stand it. 🙂
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.