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| Numrich always has 20 ga barrel blanks. I assume you want a smoothbore? If you want DOM chrome moly tubing, try a tubing house like Chicago Tube and Iron. Shotgun barrels are usually made from lesser steel, but you know that. Hell, as you know, shotgun barrels have been made from everything from twist iron and "steel", to 4140 and everything in between. I would use 4140. |
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| Working pressure is around 10000 to 13000 psi I believe a bit more then a 12ga. I believe they proof them some where over 20000psi |
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| Might be hard to find tubing with a .615 ID; might have to hone a smaller ID. From "The Standard Directory of Proof Marks", proofs of 20 guages vary with the country but are around 14-15000 psi. |
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| Jim was it you that I was talking to about a 20g a Ar platform rifle?? This wouldn't happen to be that would it??? www.KLStottlemyer.comDeport the Homeless and Give the Illegals citizenship. AT LEAST THE ILLEGALS WILL WORK |
| | | Posts: 2534 | Location: National City CA | Registered: 15 December 2008 | 
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| Yes, that would be the one. I have already done a great deal of the work but I am exploring several variations on my idea. |
| | | Posts: 222 | Location: Central Iowa | Registered: 16 May 2009 |
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| >DPCD, I saw those but was unsure of the dimensions but they are on the list if I don't find something better. |
| | | Posts: 222 | Location: Central Iowa | Registered: 16 May 2009 |
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| | | Posts: 2534 | Location: National City CA | Registered: 15 December 2008 |
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| Thank you |
| | | Posts: 222 | Location: Central Iowa | Registered: 16 May 2009 |
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| The pressure increments will vary with the shot weight and the burning rate of the powder. ASME code pressure vessels are hydrostatically tested at 1.5X the operating pressure. I would guess that you should look at breech pressure and muzzle pressure and make sure you have way more than 1.5X safety factor. quote: Originally posted by impingement:
Guys, I need some help. I am less familiar with shotguns and I have been commissioned to develop a project in 20 gauge.
I could use help in locating the following information:
1.) Source of unturned Shotgun barrel blanks (need 1.1 OD) or very thick walled tubing with a reasonably close ID so time spent finishing will be at a minimum.
2.) Pressure data for any 20 gauge loads that includes the pressure measurements in inch increments along the barrel. I have very rough calculations and would like some better info.
Right now I am working up an estimate so we can hammer out an agreement on how much for him to put in escrow and schedule the deliverables.
Any help would be appreciated.
Thank you,
Jim
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| | | Posts: 13978 | Location: http://www.tarawaontheweb.org/tarawa2.jpg | Registered: 03 December 2008 |
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| A 50% margin over the maximum working pressure is the standard for pressure vessels but pressure vessels don't normally see the fast pressure rise times that barrels see. I would go with at least 200% of minimum burst pressure as long as it is at least 150% of maximum average working pressure. When making cannons I use tubes rated to 200% of the average maximum pressure or burst pressures that are at least 300% of maximum working pressure that is intended for use. Cannon barrels typically generate similar pressures to shotgun barrels unless they are signal cannons and the the pressures are lower.
Speer, Sierra, Lyman, Hornady, Hodgdon have reliable reloading data. You won't find it on so and so's web page.
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| | | Posts: 639 | Location: SE WA. | Registered: 05 February 2004 |
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| I sat down and re-worked my locking system and figured out how to use a existing bolt and barrel; this will work to get the proof of concept off the bench. I suspect we will be making our own after that. I just realized my 5.7X28 project is back on the shelf. I guess the cobblers family always goes barefoot. |
| | | Posts: 222 | Location: Central Iowa | Registered: 16 May 2009 |
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| If you use a piece of 4140 and heat treat to 35RC it will have a yield strength of 150Kpsi give or take a bit. plenty good enough for a shot gun barrel. hell for that matter use it annealed and it's at 80Kpsi funny thing is 12L14 has the same yield 80Kpsi www.KLStottlemyer.comDeport the Homeless and Give the Illegals citizenship. AT LEAST THE ILLEGALS WILL WORK |
| | | Posts: 2534 | Location: National City CA | Registered: 15 December 2008 |
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