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Double Rifles, Single Shots & Combinations >> Building Double Rifles & Gunsmithing

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twobobbwana
.333 member


Reged: 25/11/11
Posts: 287
Loc: Queensland, Australia
Water table
      #336559 - 13/01/20 11:57 AM

Folks,

I have seen comments from double rifle builders that the shotgun action had to be adapted for double rifle use by extending the length, width and depth of the water table in order to deal with the increased pressure of the double rifle cartridge.

I have seen a "formula" for gun weight - ....% barrels, ......% action......, ...... % butt stock.

But is there a formula for water table dimensions ???

I can see how increasing the depth of the bar leaves more strength in that area. I have seen reference to the strength of Webley "screw grip"(?) and Winchester Model 21 actions due to their long bars/water tables and I have seen reference to broadening the bar at the breech end in order to strengthen the action for double rifle use..............leaves more material in the "elbow" between the breech face and the bar where the greatest flexing will take place - bolsters serve the same purpose.

Barrel diameter - at the breech - will be determined by pressure and desired gun weight, "weight between the hands" etc (good way to increase overall gun weight without destroying handling) and that will give you breech face dimensions. But how does this equate to water table dimensions ???

I'm looking forward to the input of you gunmaker and like minded folk.


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Huvius
.416 member


Reged: 04/11/07
Posts: 2986
Loc: Colorado
Re: Water table [Re: twobobbwana]
      #336561 - 13/01/20 12:51 PM

I'm not aware of any formula for it.
My guess is that when nitro powders developed, makers proved (or attempted to prove)existing actions and built up from there to where the actions could pass proof.
Steel technology saw improvements during the same time period too.
Also, you will notice that a double rifle action bar is generally not much narrower than the balls/fences of the action whereas a shotgun action has a much narrower bar. That's why rifles built on shotgun actions often look a little wonky compared to benchmade nitro rifles.
I know of a Purdey hammer double that actually cracked in the corner and I think we all witnessed an Alex Henry not long ago with the same sort of failure. Surely from shooting full nitro loads in these BPE rifles.

--------------------
He who lives in the past is doomed to enjoy it.


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twobobbwana
.333 member


Reged: 25/11/11
Posts: 287
Loc: Queensland, Australia
Re: Water table [Re: Huvius]
      #336602 - 14/01/20 11:49 AM

Huvious,

Perhaps the double rifle action holds it's width from ball/fences forward in order to accommodate a larger diameter hinge pin ???

If the hinge pin is bigger in diameter - in order to withstand increased pressures - and does not go the entire width of the knuckle - to accommodate cocking rods - the knuckle may need to be wider to suit (see I didn't say accommodate again !!!) a longer bigger diameter hinge pin.

It has been stated that shotgun actions don't handle conversion to double rifles due to the increased pressures - but there are many instances of exceptions - and that they might be shallow in the bar, lack reinforcement/width at the elbow of breech face to bar, lack hinge pin diameter, knuckle width, bar length etc,etc, etc.................but where are our "base line" dimensions coming from ????

To add confusion to the mix - if that were necessary at this point - you read of 600s being built on 500 actions, 450/400s being built on 20 guage actions etc in order to get weights down.

I believe alot of these dimensions are arrived at out of fear of actions failing and that some of these double rifles are "overbuilt" out of caution - wisely so - but perhaps, with the improved steels of today, this may not be as necessary as it used to be with "yesterday's" low carbon steels case hardened to add strength.

Bearing in mind I am aware of the necessity of the finished firearm to be of suitable weight to make it shootable given the recoil generated by the cartridge............ and for weight distribution that will make it handle.

I am interested in views................perhaps my thinking is wrong!!!??:?


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transvaal
.275 member


Reged: 19/01/13
Posts: 94
Loc: South Carolina
Re: Water table [Re: twobobbwana]
      #336617 - 15/01/20 04:47 AM

Dear Twobob...;

There does not seem to be evidence that there is or was a formula for "beefing" up the actions of British gunmakers in order to accommodate the increased pressures from shotgun cartridges to rifle cartridges. However, we have an excellent description of what a present day gunmaker, David McKay Brown did to the size of his famous round action shotgun action to have them suitable for higher pressures of rifle cartridges, starting with the .375 H&H flanged magnum cartridges. All of this is recorded in the excellent book of the history of David McKay Brown's guns and rifles authored by Donald Dallas.

What is evident in David McKay's Brown's example is that he used his experience as a gun and rifle maker as well as good engineering practices and higher strength steel to accomplish his task at hand.

We see that on page 122 of Dallas's book that Brown uses for his steel in both his guns and rifles, EN-34 for actions and parts to be casehardened (EN-32 was formerly used, as common in the trade) and he uses EN-24 for working parts, EN-45 for springs and EN-19 for barrels.

Of course, we should remember that the Scottish round actions have always been considered more stronger than the typical side lock and boxlock actions of the gun trade in the UK because of for at least one reason that the design that has holes drilled (and few at that) in areas that minimizes risk of action strength reduction. (Note: I have no evidence that this is correct, nor have I found any technical data to support this assumption, but it appears practical and reasonable) On page 99 of the same book, Brown tells us that when he resized his shotgun action for the first .375 H&H flanged magnum cartridge that...."The bar of the action was lengthened by 1/4", the back of the action was increased(made thicker)by 3/16" and the depth of the action was increased by 1/16". The joint/hinge pin was fully supported across the entire action knuckle.....The centre of the radius of the rear barrel lump was lowered so that when the barrel are closed the radius(known as the circle) comes into contact with the matching radius(known in the trade as he "draw") within the action slot. This was designed to take some pressure off the joint pin." (Note: this is a very very important mechanical and engineering design issue that most amateur gun and rifle makers do not understand and therefore do not take into account when they are building a double rifle from a double shotgun action--and it is not just amateurs who do not know this but individuals who are "professional gunsmiths". Holland & Holland is pne of the most well known maker who has even redesigned the "circle and draw" to make them stronger on their double rifles. H&H double rifle now even have a replaceable draw.)

In the following paragraph Brown (via Dallas) says that: ...."There was no need to fit side bolsters as required on side lock double rifles." (This statement of course, adds credibility that the Scottish round action must be stronger than the side lock and boxlock actions). Brown says futher: "Disc set strikers are a NECESSARY inclusion in double rile design. The nose of the striker has to be of a smaller diameter than that of a shotgun." (another item missed by some amateurs and professionals) Continuing on he says: "The pressure is much greater on a rifle and so a smaller area at the nose reduces the backward pressure and should the smaller diameter striker be snapped in two when on safari, it can easily be replaced with the spare kept in the well of the grip cap. Another design feature of the strikers is a collar or flange on its main body to act like a valve. Should any gases enter the striker hole, the striker would be forced back with the flange of the striker coming against the shoulder and thereby seal the hole preventing the powerful gases from getting into the head of the stock." (It should be noted that the striker and its flange design spoken of by Brown is a feature that the best double rifle makers have built into their actions for many decades).

On the following page we read that the next cartridge size that Brown built double rifles was the the .470 Nitro Express, and Donald Dallas records this: "Due to the increased power of the .470 Nitro Express the action body had to be scaled up even further to take the cartridge. The diameter of the joint pin was also increased from 5/16 inch to 3/8 inch"......"Soon other even bigger double rifles followed, again with the action being beefed up to compensate for the bigger pressures". (Note: David McKay Brown's double rifles built include the .577 and .600 Nitro Express).

Bob; I suspect that a form of the above has been the process that all the double rifle makers have progressed through in the engineering and building of double rifles, and is very similar to what Ben posted in his response to you.

Maybe and hopefully Mark Mitchell, the renown double rifle builder to the trade in Scotland, who is a member of the forum, will add knowledge to this post. Then we will have information from a master not from an amateur like me.

Kindest Regards;
Stephen Howell

Edited by transvaal (16/01/20 08:00 AM)


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Pugwash
.300 member


Reged: 24/03/07
Posts: 100
Loc: Scotland,UK
Re: Water table [Re: transvaal]
      #336658 - 15/01/20 07:59 PM

Stephen has raised an interesting point which is really the truth of the matter.There is no formula to any of this and many people try to over analyse it all.
Im convinced in the past that the actions were just beefed up to take the pressures needed for the rifle cartridges.As explained by McKay Brown,To extend the action backwards from the face is pretty standard stuff.I'm sure the actions were lengthened to reduce gape.If the action opens less its quicker to open and close on reloading.You will also generally find that rifles with a Dolls head,or Greener or Kirsten type bolt will be made without bolsters.The third grip will help to stop the face from rotating backwards when fired.Rifles such as an H&H or Purdey with the hidden bites have no mechanical means of stopping the face from rotating backwards so the bolsters are introduced at the root of the face to strengthen that area in the hope that it won't move.
Usually fixed pin boxlocks have a larger diameter crosspin because thay have the cocking limb pin running through them.The crosspin on H&H type rifle is really dependant on the action size but not overly large.The Rifle should be jointed onto the draw and this will hold everything together.This will take the bulk of the strain.Another place of added strength would be the thickness of the action between the lump slots and the cocking limb slots.This is considerably thicker on a rifle than a shotgun which really adds to the flat width as asked in the original question.I haven't even mentioned back action sidelocks yet(Like the H&H) which is another strengthening method.
Sorry this answer is a bit all over the place.Double rifle action design is a big subject and at the moment I dont have time to write a lot about it.I hope this may answer a few questions and maybe sometime I'll have time to write a bit more about it.


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transvaal
.275 member


Reged: 19/01/13
Posts: 94
Loc: South Carolina
Re: Water table [Re: Pugwash]
      #336666 - 16/01/20 02:31 AM

Mark;

Thank you very much for your very quick reply to Bob's question. We are most grateful that you stopped your double rifle work for some time in order to add significant information that you have learned. I am certain that your comments will be of much interest to us on why the addition of bolsters is deemed necessary on actions without Greener style crossbolts or other means of holding the barrels tight against the face of the actions.

If you have time in the future to comment further on the current discussions in the trade on double rifle actions, we will be extremely grateful as well.

I hope that you are warm and dry from the cold winds of Scotland this winter.

Sincerest Kindest Regards;
Stephen Howell
Blythewood, South Carolina USA.

Edited by transvaal (16/01/20 07:49 AM)


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twobobbwana
.333 member


Reged: 25/11/11
Posts: 287
Loc: Queensland, Australia
Re: Water table [Re: transvaal]
      #336690 - 16/01/20 12:01 PM

Gents,

I find this topic fascinating and thank you all for your input.

I'm a bit inclined to believe a lot of these dimension changes to improve strength involve a lot of paranoia/"vibe" more than engineering calculations/principles. Perhaps the change to modern steels also complicates this discussion. When dealing with low carbon steels "bigger meant stronger" whereas with newer steels the elements of the action could be smaller while being stronger.

I think a lot of these changes were made due to "what might happen" not what failures have occurred.

In an effort to make these guns of suitable weight to make the finished gun shootable they certainly can afford to have "overbuilt" actions.

I mean no disrespect to anyone when I say this. I'm "all ears" when it comes to the knowledge you guys bring to this discussion.

Transvaal your bedside table reading must be very similar to mine because it is the Donald
Dallas book on David McKay Brown that generates my original question. Fantastic book !!!

Does anyone have the Donald Dallas Holland and Holland book ??? Does it go into the same "manufacturing/mechanical" detail/process that the David McKay Brown book does ???

Vic Venters" book is also "to hand" along with Shotgun Technicana by Michael McIntosh and The Hammerless Double Rifle by Alexander Gray. Shooting Sportsman articles also drive some of this "inquisitiveness".

Vic Venters if you're viewing this it's about time you did another book as you've got plenty of fascinating material to fill it with.

With modern manufacturing methods- EDM in particular - it makes some of these processes easier to include. Adding a hardened insert into the "draw' that is changeable would allow this feature to be added to both shotguns and double rifles - of course they would be fitted "blacked down" differently to suit the guns operation.


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transvaal
.275 member


Reged: 19/01/13
Posts: 94
Loc: South Carolina
Re: Water table [Re: twobobbwana]
      #336691 - 16/01/20 12:38 PM

TwoBob;

We are fortunate to have had Donald Dallas to describe all the processes that he has done in the David McKay Brown book. However Dallas does not do this in any of his other books on the gun and rifle makers that he has written about. I am pleased that you and I jointly admire the David McKay Brown book so well, and it is my opinion that this book will go down in the written history of the UK gun trade as a jewel.

As the David McKay Brown history by Dallas is so different from his other books on the gun trade history (except for the beginning of the book with the history of Brown's life and career), I must attribute this to possibility that David Brown himself outlining and prescribing what he thought was important to discuss and illustrate in the book. The fact that the book is in so much detail and even shows photographs of the hand tools used daily by Brown's team of gunmakers will be of great interest to readers 50 and 100 years from now. Such tidbits as Brown's barrelmakers stating that he deposits soot from his blacking lamp on the barrels as a polishing abrasive after the barrels are blacked is something no other barrel blacker I have encountered has ever done or heard of doing.

What I do not look forward to is the next chapter in the David McKay Brown story. He and I were born 2 days apart in 1941, and it only a matter of short time before both of us exit. In Brown's shop I see no one standing by to take up his business and carry it forward. I hope my vision is cloudy and there is someone capable and prepared to take the business and make it even better; and better is not the correct word, I venture to say.

As a side note, back in April 2019 Donald Dallas was here in the USA in North Carolina and I gathered all my Dallas authored books that had not be signed by him and took them to North Carolina and he signed them for me.

Stephen

Edited by transvaal (16/01/20 12:42 PM)


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twobobbwana
.333 member


Reged: 25/11/11
Posts: 287
Loc: Queensland, Australia
Re: Water table [Re: transvaal]
      #336713 - 17/01/20 11:49 AM

transvaal,

You and I are sharing the same reading.

I am fascinated by his use of CNC and the time savings/benefits from utilising same.

Anybody who has attempted to fit steel via "soot and file, soot and file" can appreciate that process and the benefits of CNC/EDM. I consider them "White Man's technogeewizzery" akin to voodoo or "black magic".

My interest is deeper...........I'm currently battling with CAD with a view to CAD/CAM/CNC.

I also was interested in the "sooting" of the barrels for more polish.

Another book that helps demistify the building process, particularly the double rifle, is Ellis Brown's "Building Double Rifles on Shotgun actions".

His description of the regulation process is fantastic. Completely demistifies what has been held as a "black art" in gunmaking when it need not be so.

I would love to take a tour of Holland's/Purdey's/Westley's machine shops and see the raw material go onto the CNC machines and how long it took to "lighten" it/complete the "donkey work" so that it was fit for the artisan's hands.

Ian Clarke's operation would certainly be another tour that would be fascinating.


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twobobbwana
.333 member


Reged: 25/11/11
Posts: 287
Loc: Queensland, Australia
Re: Water table [Re: twobobbwana]
      #336715 - 17/01/20 12:10 PM

Pugwash,

Re your comments about barrels "rotating backwards" and the various means to resist the effects of this phenomenon a gent on this forum built his own Winchester 21 double rifle (.45/70) and, If I recall correctly, he left more material behind the breechface in order to provide strength there.

Another consideration in building these rifles !!!!

I wonder, at times, how some of these historic doubles, with relatively few lockup features manage to "close like a bank vault" after a lifetime of use.Though few of these guns would see use of the kind that a Clay target shotgun would..........perhaps these guns would provide the stepping off point for alot of double rifle design......particularly the sxs live pidgeon guns.

Some of these double rifles seem to be just A&D types with no crossbolt, side clips, third bite etc.

Surely it is the result of correct fitting of barrels (on face, spring and effective engagement of rear lump/draw) along with effective hardness and design........what else would it be?

If this is the case then alot of additional lockup features must, effectively, be unnecessary !!??

I particularly liked your comment re lengthening bar/water table in order to reduce gape.

I have a theory that the water table/bar should be as long as the cartridge but have no basis in fact/knowledge to support such.

Pleased you took the time to set your files aside and share your knowledge with us.


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Pugwash
.300 member


Reged: 24/03/07
Posts: 100
Loc: Scotland,UK
Re: Water table [Re: twobobbwana]
      #336724 - 18/01/20 12:31 AM

Hi TwoBob,

Just quickly,generally double rifles are thicker from the face to the back of the action than any shotgun action of a similar size.As we know,this increases the resistance to the face moving backwards when shot but also allows for the extension to be there without intefering with the leverwork.Pigeon guns tend to be a whole lot heavier than a standard shotgun action.A 12 bore pigeon gun action would in reality be the size of a standard 10 bore action.Also with the A&D actions,the rifle ones are really beefed up compared to a shotgun.As I mentioned before,the width from the lump slots to the cocking limb slots is considerably more on a rifle.Again the distance from the face to the back of the action is greater and from the flats to the top of the cocking limb slots is more.They're bigger in every area thats likely to flex.I can't recall ever seeing a rifle without some kind of third bite on it.The best ones in my experience are Dolls Heads.They make for an action very resistant to the face moving backwards.I remember Simon Clode of Westley Richards saying to me that their Rifles stay together and shoot even when they're old and rattling around.Its because of the Dolls Head.


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