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)
Awesome pistol!!!
I saw this pistol earlier (in books) but never noticed that it is a blow forward design!
The designer (s) must had been inspired by Steyr Mannlicher M1894 .
I read somewhere that blow forward designs’ work is also assisted by the force of bullet when it engages the riflings.
The bullet has left the barrel by the time the barrel starts forward, so it doesnt bring the barrel with it
No, the barrel starts moving right after the friction force makes it move forward, which means right after the bullet touches the riflings. The time bullet travels through the barrel is short, so is the path of the barrel in this time (this is the reason of confusion), but the acceleration is significant and so is the gain of the velocity. After the bullet leaves the barrel, the barrel does no accelerate anymore, but continue moving (decelerating slowly).
A few years ago a collector from California had a gun restorer make one of these from scratch. It was a full size newly made Hino – Komuro. It was a difficult project but it produced one of the most handsome guns I have ever seen
A while back I had an idea for a blow-forward pocket pistol in .45ACP. This is before I found out about the Hino-Komuro.
I love the lines of this pistol… it’s almost like some kind of space-gun 🙂
I would LOVE to see the reproduction documentation… do you remember the guy’s name or website?
Hi, Rick! And, the idea of a pocket .45 implemented? Whether is easier to alter Semmerling LM-4 automatic?
If I recall correctly, a box of about 20 of these weapons were found in a warehouse in Japan a few years back. While about 10 of them went to museums or other government agencies to study, unfortunately the rest of them were destroyed.
The story I read said that what was found was a box of the experimental double-stack magazine Type 14’s and yes most of them were destroyed because they had not been properly registered.
Leithe’s book has a photo of one as the frontispiece; serial # 56. The grips appear to be somewhat fancier. He calls it the Model of 1905, not 1908.
Ian, you say that “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”
How does that work physically? It doesn’t make sense to me, isn’t the recoil energy going to simply push on the bolt face, and therefore the whole gun, producing recoil? How can recoil push the barrel forward?
The friction between the barrel and the bullet is what pushes it forward.
The friction between the barrel and the bullet is what pushes it forward.
Hino’s gun is interesting.As a matter of fact, Captain Hino had been researching automatic weapons just before.
It is presumed that Hino’s automatic rifle had the same mechanism as Hino’s pistol.
It is speculated that Hino’s automatic rifles had the same mechanism as Hino’s handguns, but with a larger lever on the barrel, which made them more secure.
Man, I wanted to see this thing fired ! Oh, well, you don’t do that with a museum piece. Question, we have blow back and blow forwards, do we have blow side ways, or blow down (&diety help us if we have blow up)