Pressure loads

[Dean Romig]

I stand corrected - thank you Edgar. I had a gut feeling you would come on and do that. So thank you for ‘simplifying’ it all for us.
Your background in metals production, forging, etc. and your training and experience in metalurgy qualifies you to do so... so again Thank You. I used the wrong term. You used the right term and backed it up with data.

I guess my response to Mr. Rivers was meant to direct him away from any assumptions he may have been making about 75,000 lbs having anything to do with reasonable (sane) loads we should be using in these old guns.





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[Drew Hause]

Here you go
Barrel Steel Strength & Composition
https://docs.google.com/document/d/1...EK8OtPYVA/edit
A pre-WWI Titanic steel barrel was AISI 1030 with an industrial standard tensile strength (which is NOT bursting pressure) of about 75,000; which was similar to most pre-WWI Belgian sources fluid steel tubes used by U.S. makers

Turn-of-the-Century Shotshells, Powder, Proof & Ballistics
https://docs.google.com/document/d/1...UOZEFU/preview

Scroll down about 1/4 for an explanation of Parker Bros. proof testing

The 1893 Parker Bros Catalogue documented proof testing with Smokeless Powder in house
"Our guns are bored on the latest improved system for shooting Nitros, or Smokeless Powder, and all our guns are tested with some one of the most approved makes, and a tag accompanies each gun, giving the results of such a (pattern) test."

A Parker Service and Proof Load table was published in the 1930s and reproduced in the The Parker Story p. 515.
12g 2 3/4” shell Service Pressure is 10,500 psi. Definitive proof used 7.53 Drams Black Powder and 2 oz. shot with a pressure of 15,900 psi. The pressure was no doubt measured using LUP and modern transducer values would be 10-14% higher, or more than 17,500 psi.

LTC Calvin Goddard reported the same numbers in “Army Ordnance”, 1934. He wrote that Parker followed the SAAMI standards of that period: 13,700 psi proof, 9500 psi service for 2 5/8” chamber; 15,900 psi proof, 10,500 psi service for 2 3/4” chamber (by LUP) + 10-14% for modern transducer measurement.

[Michael rivers]

Ok great thanks I just need numbers to refer to.

[Michael rivers]

Originally Posted by Drew Hause

Here you go
Barrel Steel Strength & Composition
https://docs.google.com/document/d/1...EK8OtPYVA/edit
A pre-WWI Titanic steel barrel was AISI 1030 with an industrial standard tensile strength (which is NOT bursting pressure) of about 75,000; which was similar to most pre-WWI Belgian sources fluid steel tubes used by U.S. makers

Turn-of-the-Century Shotshells, Powder, Proof & Ballistics
https://docs.google.com/document/d/1...UOZEFU/preview

Scroll down about 1/4 for an explanation of Parker Bros. proof testing



The 1893 Parker Bros Catalogue documented proof testing with Smokeless Powder in house
"Our guns are bored on the latest improved system for shooting Nitros, or Smokeless Powder, and all our guns are tested with some one of the most approved makes, and a tag accompanies each gun, giving the results of such a (pattern) test."

A Parker Service and Proof Load table was published in the 1930s and reproduced in the The Parker Story p. 515.
12g 2 3/4” shell Service Pressure is 10,500 psi. Definitive proof used 7.53 Drams Black Powder and 2 oz. shot with a pressure of 15,900 psi. The pressure was no doubt measured using LUP and modern transducer values would be 10-14% higher, or more than 17,500 psi.

LTC Calvin Goddard reported the same numbers in “Army Ordnance”, 1934. He wrote that Parker followed the SAAMI standards of that period: 13,700 psi proof, 9500 psi service for 2 5/8” chamber; 15,900 psi proof, 10,500 psi service for 2 3/4” chamber (by LUP) + 10-14% for modern transducer measurement.

Great! Thanks so much for that info. I just need to know facts instead of assumptions.

[Drew Hause]

Michael: this is important
Tensile strength is only a part of the equation for estimating bursting pressure. If the barrel is made of Twist with a 50,000 psi tensile strength, that does NOT mean that it will withstand a 10,000 psi load by a factor of 5.

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) so does not work well for unobstructed shotgun barrels; which are not designed to be pressure vessels as one end is open and the pressure rises and falls quickly.

The Hoop Stress Formula doesn't reliably predict shotgun barrel failure either
Shotgun barrels are "thin wall cylinders"
σ = pr/t
p= pressure; r is the inside radius; t is the wall thickness

BTW: 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 burst at only 5,600 psi.

[Michael rivers]

There’s no argument here all I need to know is what test did Parker’s bro’s do on there barrels
So no ones right or wrong I’m asking for data that Parker bro’s held.

[Mike of the Mountain]

Originally Posted by Cameron Thraen

Read 'Finding out for myself' series of articles by Sherman Bell published in The Double Gun Journal. Excellent work reported on proof loads and gun failure. You will be surprised at the pressure required to cause failure.

Cameron, if I remember correctly, Sherman Bell used modern proof loads to test those guns, and there were a lot of guns. I remember he had some movement between the hook and hinge pins but no barrels let go. Some of those guns surprised him that they held up as well as they did. Great series of articles.

[Drew Hause]

The Double Gun & Single Shot Journal "Finding Out For Myself" series by Sherman Bell with technical assistance from Tom Armbrust
Vol 10, Issue 2, Summer 1999, Part 1, p. 9
Vol 10, Issue 4, Winter 1999, p. 21 - Destructive testing of Parker GH Damascus
Vol 16, Issue 2, Summer 2005 - Destructive testing of Parker VH Vulcan Steel
Vol 17, Issue 3, Autumn 2006, p. 12 - Destructive testing 8 Damascus doubles
Vol 17, Issue 4, Winter 2006, p. 28 - Destructive testing 7 Damascus
Vol 18, Issue 1, Spring 2007 -
Destructive testing on a Damascus barrel with thinned walls; calculated by O.D. - I.D. and not measured.
Destructive testing using various obstructions, including a 20g shell.
Destructive testing using a shell loaded with 3 1/4 Drams by volume or 56 grains of Unique (similar to “Infallible”) with 1 1/4 oz. shot. The chamber burst with the first shot.
The 3 1/4 Dram Equivalent load is 24 grains of “Infallible”.
Vol 19, Issue 2, Summer 2008, p. 18 - Destructive testing 1 Damascus, 6 Twist
Vol 20, Issue 3, Autumn 2009, p. 108 - Destructive testing 1 Damascus, 5 Twist “Bottom-Of-The-Barrel Wall-Hangers”

The Remington Proof Loads used by Sherman Bell and Tom Armbrust were measured to be 18,560 psi.
Total 28 vintage doubles/54 Twist and Damascus barrels + 2 Vulcan (Fluid) Steel

[Jay Oliver]

That is a great resource right there...Thanks for posting that Drew! What a valuable list.

I have been wanting to get some of those articles and back issues and didn't quite know where to start.

Thanks again!

[Cameron Thraen]

I have read each article. The work they completed, with precision and attention to detail, was excellent. If only I had this information in my early days when I either passed on or sold a few really nice Parkers and other Damascus barreled guns on the old gunsmiths advice "wall hanger, shoot it and you'll lose your fingers". I remember, long ago, a particularly stunning Parker D that I could have purchased except for a gunsmith's opinion that he could detect a 'stretching' in the Damascus at the breech end so I passed. Sigh.