Japanese Rollerguns (Twin Rail)

[popgun pete]

They say a picture is worth a thousand words, so here is the Japanese rollergun using the "caterpillar track" flat band system. These guns have been around since before WWII, but not a great deal is known about them. This drawing is a reconstruction of an example owned by Ron Mullins. Unlike many examples this one has fabricated brass parts, when often they are brass castings with a high level of surface finish. Wire loops and rods are formed from brass by what are probably hand craft methods. All spring functions are based on rubber strips and bands.

Few examples show the green corrosion of frequently submerged brass parts that are wetted by the adjoining soaked timbers, so I believe that these weapons are surface interface shooters rather than guns carried by divers. Certainly some have been carried by divers, but hydrodynamic drag and carriage to slide friction, including potential racking or twisting, make them more likely as having the power stroke occur in the air. But that is just a personal opinion.

Some guns bear patent numbers on small anodized alloy name plates, however these numbers and often English replacing the Japanese characters have shed no light on the gun's earliest origins. Possibly WWII destroyed the records and history of these weapons, however it seems certain that guns have been made subsequent to that time. Investigations of patent records in Japan have been fruitless as the number series displayed on the guns pre-dates the existing patent number system in Japan.

Various inquires over the years directed towards Japan have drawn a blank. John Warren, Ron Mullins and myself spent years on it, so before we all forget what we found I decided to put this post up. For views of the actual guns visit John Warren's "Rocknfish" web-site. Jack Prodanovich had an early example presented to him which has been subjected to much study, it has the hook and metal ring (or loop) system reversed to that seen on this example for the attachment of the bands to the sliding carriage and the timber stock.

Although rare there is also a monorail version with a central brass rail replacing the twin brass rail system.

The Japanese rollerguns came in different stock lengths and had different spear diameters, some had in-built reels buried in the mid section of the stock, but by modern standards all are small guns in terms of their overall length and propulsive power (due to the flat rubber strap bands used on these guns).

["Yard-Sale Josh"]

That thing is gnarly looking, cant 100% tell what i'm looking at in the picture but I get the idea. Thanks for sharing pete!

[manoa matt]

Ahh, the Tairyo! Neat little guns. It appears the trigger does not conform to the trigger design rules and needs a bias spring, or alternate pivot placement. I found this site that discusses it a bit more. The third photo shows how they solved the issue. http://home.earthlink.net/~rockfish1...with_dart.html

Pete your comments on surface use make sense when compared to the "harpoon gun" as found in the Popular Mechanics Encyclopedia Set from 1952 (I actually own the complete encyclopedia set). The design and construction is very similar.

I can't remember where I got them, but the last 3 photos from a French publication show guns of similar design with sliding piston/plungers to propell the spear shaft

[popgun pete]

Originally Posted by "Yard-Sale Josh"

That thing is gnarly looking, cant 100% tell what i'm looking at in the picture but I get the idea. Thanks for sharing pete!

There is a plan view showing the twin rails from above on a 3 view diagram of that gun, but right now I can only find the version with the two perspectives, side on and looking up from underneath.

You can see the first gun that we looked at here (Jack's gun): http://rocknfish.com/Early_Rollergun.html

Ron Mullins has it now, it is in the "museum of spearfishing history".

[popgun pete]

Originally Posted by manoa matt

Ahh, the Tairyo! Neat little guns. It appears the trigger does not conform to the trigger design rules and needs a bias spring, or alternate pivot placement. I found this site that discusses it a bit more. The third photo shows how they solved the issue. http://home.earthlink.net/~rockfish1...with_dart.html

Pete your comments on surface use make sense when compared to the "harpoon gun" as found in the Popular Mechanics Encyclopedia Set from 1952 (I actually own the complete encyclopedia set). The design and construction is very similar.

I can't remember where I got them, but the last 3 photos from a French publication show guns of similar design with sliding piston/plungers to propell the spear shaft

Those last 3 pages are from the 1957 French "Systeme D" booklet on how to make your own spearfishing gear. They show the side-slotted barrel guns that the Champion "Arbalete" made obsolete as they were less reliable than it was due to their more complicated parts and the need for running clearances. The underwater environment is hard on guns with too many close-fitting parts due to salt, sand and marine detritus which the shore-based diver often encounters.

My line drawing pre-dates the discovery of the more or less complete older gun, so we knew what to look for when one eventually turned up for sale. Personally I believe that the cast parts guns are older and that the thin plate carriage gun is an attempt to lighten the gun and reduce the impact of the carriage slamming into the stops at the end of the rails. So far there are two like that that have been found to my knowledge, whereas there are quite a few of the cast parts guns around and they are more finished in their woodwork. The diagram was to appear on "skindivinghistory.com", but the site never progressed and that diagram has been gathering dust for years, the file for it is locked up in my old computer which died some years ago, but I had a printout which I only found yesterday.

New: I have now updated the diagram with the correct slip tip and added the comments on the swinging arm underneath the stock that does two jobs.

[popgun pete]

I did not put the reverse angle tooth, single-piece trigger in the trigger mechanism design rules because it is obsolete. It was used in early tail-pusher spearguns without a sear box as such. Here is the diagram for it.

Also used in some weaker crossbows, the diagram shows why you need to be careful with it.

NB. Now added to that trigger mechanism design rules thread.

[popgun pete]

Note that the diagram is a bit of a composite as there are other guns besides the "Tairyo", there is a "King" model with a brass plate pivoting safety lever blocking the trigger instead of the swinging arm. It also has a line slide and a similar construction slider that attaches to the slip tip. Also these "King" guns have a simple wire frame clip under the muzzle that holds the shooting line, there is no line wrap system as such. The guns seem to come from Osaka, Japan, but when questions were sent to the city's administration there was no info available, although a reply was received regretting their inability to help.

Another speargun from Japan is/was the "Hiroshima" band speargun, but it is totally unrelated to the rollerguns, having a bifurcated timber stock totally enclosing the spear shaft.

[popgun pete]

It is interesting to note that the original rubber strap bands are manufactured from a red rubber. Vulcanized rubber contains a number of ingredients besides natural rubber (and today synthetic rubber, or a mix) as there are binders, stabilizers and fillers which modify its properties and strengthen it. A common material to add is fine particulate clay and that is what confers the red color and a degree of mechanical strength. The most common addition is carbon black as that provides molded rubber with much of its improved strength and wear resistance, but that is absent from these bands which are designed to be stretchy or elastic. A truly elastic material returns to its original dimensions and returns the energy used to deform it without loss, but rubber bands are not truly elastic in that sense. The thin red rubber straps have a small cross section, so they are more limited in energy storage or you would risk pulling them apart. The material used may have been sourced from a support webbing such as that used in chairs rather being especially made, however there is no info available on that aspect. Automotive rubber belts (non-reinforced) often provided bands for early spearguns elsewhere, such as in France.

Note that the brass cylindrical rollers had slightly concave surfaces to help the bands track and stay centered on the rollers as they travel around them during the shot. The dynamics of the bands and their twisting and what happens at the nip where they first contact the turning rollers would be interesting to analyze with an underwater video. Even guns used by poking the muzzle through the surface will have an interaction of the bands and rollers with the water. It is also possible that the crash of the sliding carriage into the muzzle stops may be ameliorated by a submerged impact.

There is a much later version of the "Tairyo" gun based on a plastic tube rather than the twin brass rail system, the sliding carriage replaced by a pusher element in the tube which has a longitudinal slot in the top for the band attachment to poke through and provide the drive to the shaft. Used fully submerged this tube would be a water pump greatly slowing the shot, so the surface interface shooter seems a more likely prospect here.

There is a tradition in Japan of raft guns where fish are shot from the surface by poking the gun down through the surface, the fish being lured into shooting range by bait or, would you believe it, floating decoy models of fish! The "Hiroshima" gun mentioned in the previous post was produced as both a raft gun (with a long pole mount body, the trigger was remotely operated by a cord) and a pistol grip rear handle version for underwater use. This gun was advertised as the "Nakaoka" gun and was available on the Web some years ago at a very high price, but exhibited truly breathtaking craftsmanship in the traditional Japanese woodworking style.

[popgun pete]

Originally Posted by popgun pete

There is a plan view showing the twin rails from above on a 3 view diagram of that gun, but right now I can only find the version with the two perspectives, side on and looking up from underneath.

You can see the first gun that we looked at here (Jack's gun): http://rocknfish.com/Early_Rollergun.html

Ron Mullins has it now, it is in the "museum of spearfishing history".

I finally found the three view drawing, so here it is.

[popgun pete]

While looking through old files I found the nameplate photos showing the different spear diameter gun sizes, these being from the "King" label guns. Most notable difference in these guns was a swivelling side plate safety that swung a bar behind the trigger. You can just see the safety device in the corner of these photos. Note at this time the labels are in English.

[popgun pete]

A 7mm spear "King" Japanese Rollergun is for sale here:
https://www.ebay.com.au/itm/334625418214
The spear is probably a later replacement as originally these guns use brass rod spears, however they always use a steel detachable tip even though on most guns these are usually missing. The flat rubber bands and end pull rings are missing that are used to hook over the sliding carriage hooks, but these would be reasonably easy to replace.

[popgun pete]

Originally Posted by popgun pete

A 7mm spear "King" Japanese Rollergun is for sale here:
https://www.ebay.com.au/itm/334625418214
The spear is probably a later replacement as originally these guns use brass rod spears, however they always use a steel detachable tip even though on most guns these are usually missing. The flat rubber bands and end pull rings are missing that are used to hook over the sliding carriage hooks, but these would be reasonably easy to replace.

Only one bid and went for the starting price of 199 bucks. Years ago there would have been a bidding duel for it, but these guns are not the mystery they once were.

[popgun pete]

The concave surface muzzle rollers that I mentioned earlier in this thread for maintaining tracking of the flat rubber belts as the bands contract during the shot and while being dragged rearwards for gun cocking. Note there are no fender straps from the axle ends running back to the stock, these were added to keep the shooting line from being dragged into the roller system on some models.

[popgun pete]

This is one of the original brass spears for the Japanese rollerguns, with just the front and rear ends being shown here. The pointed end is what the detachable steel spear tip sits on and the short metal peg at the rear pointing downwards acts as the line slide stop as well as an anti-rotation device on the spear. This small peg runs in the narrow groove cut in the top of the timber barrel and exits out via a keyhole shaped slot in the muzzle. The spear is thus supported at the rear by the sliding carriage and by the vertical muzzle plate at the front, hence the spear itself does not sit in a guide track. Instead the twin parallel rails provide the shaft guide function. On the earlier spears a cord whipping as seen here serves to hold the detachable spear tip to the spear, later models have another hole punched tab on the shaft similar to the line slide to tie the spear tip to.

[popgun pete]

Another Japanese rollergun has appeared on eBay, this one has the swinging arm safety also seen on Jack Prodanovich's specimen of the gun. This example is a longer version and appears to lack an anodized nameplate. The deflection straps or side struts that keep shooting line from tangling on the rollers are not present either which indicates they were either a later addition or are unnecessary if the shooting line is held by a passive clip under the front of the muzzle which is seen on the "King" model of the guns. Any shooting line wraps freed from a rear mounted line hook release arm have to clear the roller axle without snagging during the shot.

https://www.ebay.com/itm/285761704652