Vintage Barrel Steel Composition

[Dean Romig]

Great work, as usual Drew.





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[Kirk Mckinney]

Yes I am new to vintage Sxs and reloading. Great article on barrel composites and strengths. Am I understanding it correctly. I would have to shoot a load that makes about 65k plus psi to burst my barrels on my 1929 sterlingworth is that correct ???

[Drew Hause]

Oh my Kirk. But there are no inappropriate questions concerning double gun barrel safety.

1. The A.H. Fox Gun Co. used Krupp steel on the graded guns from the beginning, with “Sterlingworth Fluid Compressed Steel” for the lower priced Sterlingworth. A Sterlingworth brochure in 1911 mentioned “chrome-nickel and vanadium steel” barrels and “Chromox High Pressure Fluid Steel” was introduced in 1912
https://books.google.com/books?id=eG...J&pg=PA137&lpg

2. I am not aware of a tensile strength report for Sterlingworth steel. Bohler "Antinit" (Rostfrei Laufstahl chrome-molybdenum-vanadium introduced 1912) was and is extremely good stuff with a reported tensile strength of 138,000 psi.

3. Tensile strength is only one part of the bursting formula. If the barrel is made of fluid steel with a 100,000 psi tensile strength, that does NOT mean that it will withstand a 10,000 psi load by a factor of 10.

Barlow's formula P=2 S t / D
P=Bursting pressure in psi.
S=Tensile strength of material in tube wall.
t=Wall thickness in inches.
D=Outside diameter in inches.

Barlow’s refers to a pipe capped at both ends with a static pressure (a pressure cylinder). Shotgun barrels are not designed to be pressure vessels as one end is open and the pressure rises and falls quickly. There is essentially NO applicable bursting formula for shotgun barrels.

4. Wallace H. Coxe, in “Smokeless Shotgun Powders: Their Development, Composition and Ballistic Characteristics” published by E.I. du Pont de Nemours & Co. in 1931 cites a study in which a fluid steel barrel was cut to 9” and capped, then a series of progressively increasing pressure loads fired. The barrel cap was blown off and barrel split at 2 Long Tons LUP or about 5,600 psi using Burrard’s conversion to modern piezoelectric transducers.

5. Sherman Bell's destructive testing of a Parker GH with Dam 3 and a Parker VH with Vulcan Fluid Steel was published in The Double Gun Journal Vol. 10, Issue 4, Winter, 1999, “Finding Out For Myself” Part II and Vol. 16, Issue 2, Summer 2005, “Finding Out For Myself” Part IX.
Both guns were subjected to sequentially higher pressure loads at about 2,000 pounds/square inch (psi) increments. The GH testing started at 11,900 psi and one chamber ruptured at 29,620 psi. The VH started with a Proof Load of 18,560 psi. Both chambers bulged at 29,620 psi and ruptured at 31,620 psi.

6. No one on the internet can tell you at what pressure YOUR Sterlingworth barrels would burst. Recommendations for barrel evaluation may be found here:
https://docs.google.com/document/d/1...vwLYc-kGA/edit

[Kirk Mckinney]

Drew thanks for the clarification. As I said I'm new. Could I ask you what you would consider a safe pressure for this gun. 6000 and down 7000 and down, 8000. If it were yours where would the limit be for you. My skeet loads are 6150 and down. But hope to develop a non toxic load for ducks. But I want to be safe. And want to preserve the integrity of my beautiful gun.

[Drew Hause]

Here you go Kirk
https://docs.google.com/document/d/1...vwLYc-kGA/edit

https://docs.google.com/document/d/1...UOZEFU/preview

1914 A.H. Fox Gun Co. catalog recommended 12g loads (courtesy of David Noreen)
DuPont, “E.C.”, and “Schultze” Bulk Smokeless 3 Dram 1 1/8 oz.
Dense Infallible 20 - 24 grains with 1 1/8 oz. shot
Dense Ballistite 20 - 22 grains with 1 1/8 oz. shot

1 1/8 oz. 3 Dram Equivalent of BULK Smokeless was 6500 - 7500 psi.
1 1/8 oz. 3 Dr. Eq. of DENSE Smokeless was 8,500 - 10,000 psi.

[Kirk Mckinney]

Cool. Thanks a million Drew. So I guess I was playing it real safe. If I could ask just one more quick question. Do you think it would hurt my barrels to shoot bismuth with a fiber wad ? Thanks again for the info it will help me very much. See you in the field

[Drew Hause]

Bismuth is as soft as lead. You should ask the manufacturer for the load pressure; RST is happy to provide that information.