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THE TANEGASHIMA BREACH PLUG ( BISEN )


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The Matchlock entered Japan aboard a small Chinese cargo ship in 1543. The ship landed on Tanegashima Island and by chance on board were 3 Portuguese, ... two of whom carried Matchlock muskets. These were the very first Europeans to land upon the shores of Japan. To make a long story short, The lord of the island, Tokitaka, purchased two of the matchlocks which were sold “for a great profit” and tasked his sword maker with producing copies. Japanese swordsmiths were expert blacksmiths/swordsmiths, but the blacksmith/swordsmith had difficulty in forging the barrel so that the breach plug screw on the end could be fitted or so the story goes. The screw could supposedly be removed to allow the barrel to be easily cleaned. The truth of the matter is that contrary to popular belief the breach plugs on the Portuguese Matchlocks were in all probability not threaded at all but rather sweated into place. This was done by heating the breach end of the barrel and then inserting what had previous to the barrel being heated ( the heating causing the barrel opening to expand ) a slightly larger diameter plug of steel. When the barrel cools the plug ( breach plug ) is now impossible to remove the fit is so tight.

 

 

Supposedly a year later, a Portuguese blacksmith arrived in Japan ,and he was persuaded to pass the secret of the breach plug by as legend goes ... the Portuguese blacksmith was offered the hand in marriage of a lovely girl called “Wakasa” ( the blacksmith's daughter ) as the reward for disclosing the secret of how to affix the breach plug into the barrel. This is in all probability just legend.

 

 

Now whether or not the Portuguese had moved from the sweated in breach plug to a screw type system is questionable ( in spite of the Japanese claiming to still own one of these original Portuguese Matchlocks ). Personally I believe this is just wishful thinking that any Portuguese Matchlock survived. The matchlock in question is missing its lock I believe. I searched but I cannot find a photograph of this or some say two guns. Perhaps Piers has a photograph ?

 

 

 

Since the breach plug or Bisen is on any Japanese matchlock that I have seen have been of a threaded variety ( male thread ) and affixes to the breach by threading into the barrel ( female thread ) and quite often such a poor fit that a small flat piece of lead is added to the threads on the bisen so as to get a tight fit to the female threads of the breach .... HOW did the Japanese thread these barrels ?

 

 

It is one thing to hand file threads on the bisen, ... difficult, ... but not impossible, ... but it is bloody impossible even for a Japanese craftsman to file the female threads inside the breach of the barrel. It cannot be done ! Well you might say, ... I've seen pictures of a Japanese TAP for cutting these threads ( perhaps Taira Sawada or some other Japanese expert has explained how it was done ) but since I do not read Japanese I cannot be sure. ( SEE PHOTOGRAPH of what appears to be a Japanese TAP). Since the Japanese did not possess to the best of my knowledge TAP & DIE sets back in the late 1500's nor the early 1600's for that matter .... we see virtually no screws being made. With but very few exceptions the Japanese used tapered brass pegs to attach locks to their firearms.

 

 

So how did they cut the female threads inside the breaches of their matchlocks ? Perhaps the Japanese Scholars have already explained the process, ... but if they have, ... they to the best of my knowledge never published the answer in English.

 

 

 

Here then is my theory ( if stolen I assure you quite by accident due to my not reading Japanese ). The item that appears to be a TAP was inserted cold and probably coated with clay into a pre heated ( red hot ) barrel ... a tight fit. The breach was then hammered all around driving the barrel steel into the groves of the FALSE TAP. The tap was then removed by unscrewing and the process repeated by screwing the cold false tap into the poorly executed female threads. The barrel was repeatedly hammered until a decent fit was achieved and the FALSE TAP removed permanently. A BISEN was then filed by hand to match the threads on the FALSE TAP ... a tedious but possible task. This explains the rather poor fit of many bisen and the reason a small thin sheet of lead was wrapped around the bisen to ensure a nice tight fit on many bisen I have examined.

 

 

I have attached several photos , showing the different methods of attaching the breach plug or bisen, a FALSE TAP, a Treaded Breach, and a Bisen. As always any errors or omissions are mine alone.

 

 

... Ron Watson

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Sounds like one way to do it. I wonder. We know that threads preceeded by quite a while in wooden applications. Gears, hubs etc. on wooden axels. Another way to create female threads could be to grind them. Using abrasives on hard wooden jigs, gradually increasing taper to slowly increase pitch etc. John

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Ron Watson wrote:

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Supposedly a year later, a Portuguese blacksmith arrived in Japan ,and he was persuaded to pass the secret of the breach plug by as legend goes ... the Portuguese blacksmith was offered the hand in marriage of a lovely girl called “Wakasa” ( the blacksmith's daughter ) as the reward for disclosing the secret of how to affix the breach plug into the barrel. This is in all probability just legend.

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I have an old videotape of an NHK program that is a costume drama recreation of this story/legend/what have you. It runs for about 20 minutes with Japanese dialogue, but it is a good watch. The frustration of the swordsmith coming to grips with this new weapon is well played.

 

BaZZa.

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Great write up. I suspect both methods might have been attempted at some stage. Forging the barrel around a hardened mandrel would have been possible in the beginning. Same way hammer forged barrels are rifled.

Cutting them might have been a later improvement. Possibly what you have pictured Ron, is a tool used to chase the threads and clean them up..maybe like a finish reamer.

I gave up trying to remove my bisen. It is well and truly stuck, and penetrating oil, tapping, and heating have all done nothing at all. I will have to live with it frozen, which is a pity.

 

Brian

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Dear Brian,

Removing the bisen is not all that important. The barrel can be adequately cleaned inside without its removal. It is simpler but one often finds getting the bisen properly lined up when re-installing it can be frustrating to say the least. You are probably never going to fire it anyway, and if you do at least you know the breach plug is secure :D . Wrapping emery paper around a brass rod and then using your electric drill will remove any stubborn rust from inside the barrel. Follow up with crocus cloth to give the inside a nice clean polished finish and voila you're ready for hunting Lion, or Elephant Poachers :badgrin: .

... Ron Watson

 

PS. Got your ama-ooi completed yet ??

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The fact that it doesn't have to be removed doesn't cancel out the feeling that I want it removed :lol:

I can take my Glocks down to the last part in about 40 seconds. I like to have things as they were originally. I want to be able to see the other side of the flash hole, and examine the barrel with light shining through it. Lots of advantages to being able to see the back of the barrel.

I haven't given up yet...maybe more heat, and a custom spanner that is padded. No rush....

Ama-ooi has to wait. The other one was coming along nicely, but it was not thick enough to be able to machine it down and leave the back ridge. So scrapped that one, and waiting until I can get to the metal merchants here to buy a thicker piece of brass. I alwasy seem to be at work nowdays...not even an hour to go to Metal Centre. :cry:

I'll get back to it soon enough...

 

Brian

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Dear Eric,

I mechanically translated the Essay from the National Rifle Association of Japan, ... and although difficult to understand one or two paragraphs stand out ... here is one of them from page 3 :

 

" It is characteristic of the steel structure of crystals (magnification 42) locations along the thread profile, it flows continuously. By inserting the male screw "type torsion" it after heating the breech and 鍛打 outside of the barrel, which indicates that it was formed a female screw gun cavity wall surface. And serves as a critical evidence that was created during hot forging. Those further expand the (magnification 100) of the internal thread piles, f is illustrates the crystalline structure of steel by hot forging is as described above. "

 

" .... Conclusion "

 

" The screw of hot forging has been made ​​over the Edo period to the late Edo period, Western thought never came in was proved. "

 

I get the gist of what the writer is trying to convey, ... that my theory may probably be correct that indeed rather than the female threads being cut by die, ... they were actually formed by HOT FORGING. This seems to be the first Japanese scientific research into how the female threads were produced.

 

... Ron Watson

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I seem to recall something about mechanics heating studs stuck in an engine block then letting some kind of wax melt and run down the threads. Not that you would want to heat your breach plug, I'm just wondering if the process would work.

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My first pistol was a real beauty and admired by all and sundry. It contained a terrible secret, though. Someone (no names) had applied too much heat, freezing and force, and the Bisen had broken in two. It then needed boring out and a new screw cut. It made me feel like an imposter, hiding a brand new Bizen with western-type screw in it. Since then I have been super aware of the fallibility of the Bisen itself.

 

Incidentally someone told me the other day that the first guns made in Tanegashima probably had solid, sealed breech plugs.

 

Oh, and Chris, the other pistol in question I mentioned earlier with the rusted stuck Bisen has silver inlay on the barrel right to the edge, so I am a little nervous of too much heating.

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Oh, and Chris, the other pistol in question I mentioned earlier with the rusted stuck Bisen has silver inlay on the barrel right to the edge, so I am a little nervous of too much heating.

 

That makes it difficult to heat too much but silver does have a 1,763°F melting point- I should think the steel would be red hot by then and perhaps a bit more heat than necessary....

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Dear Piers,

" Incidentally someone told me the other day that the first guns made in Tanegashima probably had solid, sealed breech plugs. " Yes, ... see my article above ... " sweated " into place as in early Portuguese matchlocks. Once something is " sweated " into place it is solid and generally cannot be removed as heating the breach afterwards also heats the breach plug which had to be cold to insert in the beginning.

 

To answer Dany C. , ... heating the breach plug would defeat the purpose as that would cause the breach plug to expand even tighter, ... what it might do is upon cooling and contracting it might break the bond between breach and breach plug. I've often done this with stuck bolts on machinery, adding a little fine oil around the area of the threads as I'm heating with some success I might add.

 

... Ron Watson

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Ron,

 

I know it sounds weird, which is why I brought it up. So, heating the breach plug could break the bond with the barrel, the melted wax gets drawn down into the threads and solidifies as the plug cools. Then when the plug has cooled and shrunk back down, it could be turned out because the wax has created a separation between the metal surfaces. Sounds possible, not sure I would try this on anything I gave much value to though. My main thinking was that this technique could prevent damage or discoloring from heating the barrel, so I was curious if it was something used during restoration projects.

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Dear Dany C.

Weird, ... not necessarily. When one gets stuck for solutions to a problem, ... it is often the weird that succeeds. The main thing is much like the first rule a Doctor should learn ( but often don't ) ... do not make the patient worse. Your idea will surely not make the patient worse, ... and is worth a try.

Often when doing restorations ... it is of utmost importance to go slow and always if possible use the original type hand tools and techniques of the time period the item was made. Patience is a virtue soon learned ( often too late ) when doing restoration or repairs on antiques.

... Ron Watson

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Try freezing the bizen and heating the barrel....

 

2nd this.

 

Perhaps a can of freeze spray and at same time a heat gun directed around the barrel. Downside is once cold it is more brittle, so might snap. This after oil and gentle heating/soak for a week or so, which I suspect has already occurred. Better guns have temp settings that should ensure no damage to the metal/inlays.

 

 

http://www.amazon.com/MG-Chemicals-Supe ... +spray+gum

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In my trade, from which I am retired, I spent many hours removing studs, bolts, plugs etc. that were salt welded into decks, bulkheads, tanks, beams etc. and were of steel or brass within steel. Sometimes it was just impossible and the had to be drilled and chiseled free since many were on tank tops containing oil and fuel etc. It can be scary using wrenches with multipliers and torches to remove plugs from bunker barges that had not been gas freed. The thing is I don't know how much heat these barrels can take even at the breech. One of the most effective methods was to heat to orange, pretty hot, and quench with cold water to break the corrosion seal. Sometimes multiple times. We did not have to worry about damage to the pieces however because anything can be repaired in the shipyard. 99 out of a hundred times this worked, with those that didn't being cut out and replaced. When you are a thousand miles out you don't give up easily, a million dollar contract is in the balance. On an antique that will never be fired again it is at what point do you weigh damage against preservation? In these cases I would err towards the preservation side. John

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Dear John,

" On an antique that will never be fired again it is at what point do you weigh damage against preservation? In these cases I would err towards the preservation side. " ............. SO WOULD I JOHN, ... SO WOULD I :clap: !

 

... Ron Watson

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