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Double Rifles, Single Shots & Combinations >> Building Double Rifles & Gunsmithing
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lucas
.224 member


Reged: 27/03/19
Posts: 3
Loc: new zeland
double rifle beginner
      #326538 - 28/03/19 11:42 AM

hi all

I've just purchased Ellis browns book on converting shotgun actions to double guns and in the back of the book is the pressure guide,im wanting to build rifles in calibres on high-pressure table which he recommends you don't do on a shotgun action so my question is do I scale up the dimensions to suit or is there a better method?

cheers
lucas

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DarylS
.700 member


Reged: 10/08/05
Posts: 27000
Loc: Beautiful British Columbia, Ca...
Re: double rifle beginner [Re: lucas]
      #326545 - 28/03/19 05:15 PM

Use real rifle SxS actions for high pressure guns - that's the answer.

The SxS rifles of the 1800's and early 1900's were not high pressure guns - about all the ctgs they were chambered for developed less than 40,000psi AND the ctgs. also had large enough rims to lower breech thrust.

Some of the newer SxS's, chambered for .375H&H and .458 Winchester are high pressure guns - ctgs. never, to be put on ANY shotgun action, imho.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V

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4seventy
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Reged: 07/05/03
Posts: 2210
Loc: Queensland Australia
Re: double rifle beginner [Re: DarylS]
      #326558 - 28/03/19 10:14 PM

Quote:

AND the ctgs. also had large enough rims to lower breech thrust.




It's actually the other way around.
For any given pressure, breech thrust increases as the cartridge base diameter and area increases.

It's x pounds per square inch cartridge pressure acting on x square inch's of base area to produce x pounds of breech thrust.

The bigger case head diameter will have the bigger base area and the bigger breech thrust.

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4seventy
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Reged: 07/05/03
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Re: double rifle beginner [Re: lucas]
      #326559 - 28/03/19 10:36 PM

Hi Lucas,
Building a double rifle on a shotgun frame for a 'high pressure' cartridge?
Don't do it.

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Huvius
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Reged: 04/11/07
Posts: 3556
Loc: Colorado
Re: double rifle beginner [Re: 4seventy]
      #326568 - 29/03/19 01:05 AM

Quote:

Quote:

AND the ctgs. also had large enough rims to lower breech thrust.




It's actually the other way around.
For any given pressure, breech thrust increases as the cartridge base diameter and area increases.

It's x pounds per square inch cartridge pressure acting on x square inch's of base area to produce x pounds of breech thrust.

The bigger case head diameter will have the bigger base area and the bigger breech thrust.




I've never been able to wrap my head around this...

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

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85lc
.400 member


Reged: 19/01/18
Posts: 1031
Loc: Georgia, USA
Re: double rifle beginner [Re: Huvius]
      #326578 - 29/03/19 03:16 AM

4seventy is correct. The larger the head diameter, the greater the thrust against the action.

For example, if a load is 40,000 psi and the case head area is 1 sq in, the thrust is 40,000 pounds.

With the same pressure and a cartridge head area is 0.50 sq in, the thrust is 20,000 pounds.

--------------------
RB

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DarylS
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Reged: 10/08/05
Posts: 27000
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Re: double rifle beginner [Re: 4seventy]
      #326583 - 29/03/19 04:17 AM

LOL - you are right - it was late or I was inebriated when I wrote that. Seems I get more things bas-ackwards these days.
But - what I got right, was to NOT make a high pressure rifle ctg. on a shotgun action.

You could make up a 3", 12 bore rifle on a good 10 bore action, likely, to produce 1,900fps with 600gr. bullets = 4,800fpe - 700gr. bullets would make it 5,612fpe. That will kill moose.

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3DogMike
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Reged: 29/01/15
Posts: 1464
Loc: Western Slope, Colorado USA
Re: double rifle beginner [Re: DarylS]
      #326591 - 29/03/19 09:08 AM

Quote:

LOL - you are right - it was late or I was inebriated when I wrote that. Seems I get more things bas-ackwards these days.
But - what I got right, was to NOT make a high pressure rifle ctg. on a shotgun action.

You could make up a 3", 12 bore rifle on a good 10 bore action, likely, to produce 1,900fps with 600gr. bullets = 4,800fpe - 700gr. bullets would make it 5,612fpe. That will kill moose.



“......That will kill Moose.....”
I should think so!

Was it Marrakai that had the “fat lady” .577 2-3/4” Light Nitro rifle built on a Greener Empire action?

- Mike

--------------------
"Will Rogers never met a fighter pilot"
- Anon

“Always carry a flask of whiskey in case of snakebite, and furthermore always carry a small snake."
-- W. C. Fields

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DarylS
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Reged: 10/08/05
Posts: 27000
Loc: Beautiful British Columbia, Ca...
Re: double rifle beginner [Re: 3DogMike]
      #326621 - 30/03/19 04:50 AM

Sounds familiar - good hog rifle!

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V

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4seventy
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Reged: 07/05/03
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Loc: Queensland Australia
Re: double rifle beginner [Re: lucas]
      #326635 - 30/03/19 09:14 PM

Lucas,
What cartridges were you thinking of, and what makes and what gauge shotgun actions were you hoping to use?

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lucas
.224 member


Reged: 27/03/19
Posts: 3
Loc: new zeland
Re: double rifle beginner [Re: 4seventy]
      #326815 - 04/04/19 06:33 AM

I wasn’t going to use an existing shotgun just the basic mechanism I was going to build it from scratch.

Also what type of steel are people using? I use 4140 high tensile to build Remington 700 action which I guess would be suitable but being a different style of rifle I thought I would ask

Cheers
Lucas

--------------------
1

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GPJ12345
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Reged: 18/08/12
Posts: 149
Loc: South Africa
Re: double rifle beginner [Re: lucas]
      #329626 - 25/06/19 03:07 AM

Lucas/Members while giving advice to Lucas , please elaborate on the shot gun action ga that is suitable for a conversion build..I spoke to a friend of mine..Johan Greyling..he mentioned that most people use a 12 ga action ..according to him this will makes for a heavy , slow target acquisition , slow handling heavy type of rifle...I am considering a .450 NE nr 2 Jeffery as my second build ..my first conversion build I am contemplating a 16 ga shot gun action building a 45-70 Government double rifle ...any comments and suggestion will be much appreciated as pointed out by Lucas as well..I need to point out as well that I want to keep the original shot gun barrels and build new 45-70 cal Government rifle barrels ...

Edited by GPJ12345 (25/06/19 03:09 AM)

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lucas
.224 member


Reged: 27/03/19
Posts: 3
Loc: new zeland
Re: double rifle beginner [Re: GPJ12345]
      #329628 - 25/06/19 05:04 AM

I’m not looking to convert a shotgun I’m aiming for high pressure rounds in a double rifle and building from scratch

Cheers
Lucad

--------------------
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DarylS
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Reged: 10/08/05
Posts: 27000
Loc: Beautiful British Columbia, Ca...
Re: double rifle beginner [Re: lucas]
      #329653 - 26/06/19 01:38 AM

Good luck, Lucas.
GP - a decent 16 bore should be suitable for BP level loads,
but know they will develop upwards of 24,000psi - 70gr. BP and 500gr. bullets. A longer case, as in the 2 7/8", will produce close to 30,000psi.

This is the level the Baikal .45/70's are suggested for, but that action is also made up in .30/06, a 60,000psi round. This suggests the shotshell action might not be a good choice for this pressure range in the larger case.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V

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GPJ12345
.300 member


Reged: 18/08/12
Posts: 149
Loc: South Africa
Re: double rifle beginner [Re: DarylS]
      #329656 - 26/06/19 03:04 AM

Great, please upload the whole process on the forum..it will really be nice to follow such a build from the start...

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crshelton
.333 member


Reged: 10/11/15
Posts: 379
Loc: Republic of Texas
Re: double rifle beginner [Re: GPJ12345]
      #329664 - 26/06/19 10:12 AM

GPJ1234,,,

There are 12 gauges and then there are other 12 gauges.
The term "heavy" may mean one thing to one person and a different thing to another.

My 9 pound .45-70 double was made on a 12 ga Beretta GR2 action and even with 26 inch barrels it is not heavy to me. To me it is well balanced and graceful with negligible recoil.

It is a bit more slender than my 9.5 pound .405 double which was made on a Simson Suhl 12 gauge action. That gun is also well balanced and almost shoots itself (like any good shotgun should).

The weight and design of both these rifles make them easy to shoot from the bench and fun to hunt with.

And lastly, the only advice that I dare to give to Lucas is to keep shopping around and researching options until you find what you like. Here is an interesting rising block double rifle made by Bradshaw here in Texas: http://www.bradshawgunandrifle.com/rising-block-double-rifle.html

--------------------
CRS,NRA Benefactor Member, TSRA, DRSS, DWWC, Whittington Center
Android Ballistics App at http://www.xplat.net/

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