Barrel wall thickness

[Stepmac]

Originally Posted by Justin Julian

This has been a great and informative thread. In that regard, what's the consensus on the safety shooting factor of this DH? I do note that the chamber/forcing cone minimum barrel wall thickness measurements are needed.

http://www.gunbroker.com/Auction/Vie...Item=304446791

To my eye those barrels look plenty thick. The safety of shooting those fine damascus barrels has been much discussed here. I suggest you find Sherman Bell's articles in Double Gun magazine. He has done extensive research and many tests shooting those damascus/twist tubes. He had a difficult time getting them to let go, even when shooting modern proof loads.

You can also buy lighter loads made specially for the older guns. Look up RST and Polywad shot shells.

Summery, you can find very safe ways to shoot and enjoy guns like these and if in good condition, they are safe when shot with proper loads.

[Richard Flanders]

Jay's long response to this question is first class. Factual, logical and to the point. I for one copied it into Word so I can refer to it without having to search for it and show it to friends who might ask the question. Thanks Jay. Very well done.

[Bruce Day]

Back to top. Persons interested might read Jay Shachter's post.

[Drew Hause]

This information was part of a separate thread, but will add it here
http://parkerguns.org/forums/showthread.php?t=10889

Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives (C.I.P) http://www.cip-bobp.org/

Shotgun recommended minimum wall thickness p.4

http://www.cip-bobp.org/sites/defaul...e/A-4-1_EN.pdf

For 10 & 12g Standard Steel................................20g Standard Steel

End of chamber - .079”............................................. ....... .075”

Just past the forcing cone/ 4” from breech - .075”................. .071”

8” - .043”............................................. ........................... .041”

12” - .030”............................................. ......................... .028”

16” - .024”............................................. ......................... .022”

20” - .022”............................................. ......................... .020”

FAQ http://parkerguns.org/pages/faq/BarrelThickness.htm

[Bruce Day]

And that correlates to what service and proof loads?

[Drew Hause]

There are three pressure measurement systems (lead crushers/LUP, copper crushers, and piezo), and two standard systems of measure units (USA/SAAMI and CIP/British/European) and two differing units (psi and tons and BAR in kg/cm sq) within each system, different proof laws by country, and differing proof laws by age.
Unfortunately, there is essential NO formula to convert BAR expressed as LUP (CIP) to PSI (SAAMI). LUP + 1000 does not reliably predict the actual piezoelectric transducer measured pressure.

That said, European (CIP) "standard" proof pressure of 850 kg per sq. cm. (BAR) = about 13,920 psi proof pressure = 10,730 psi service pressure (SAAMI)

[Bruce Day]

So are you saying that the commission wall thickness recommended minimums correlate to the commission stated proof loads and service loads? So that if these are the commission recommendations, where do some of the figures that we see thrown out come from? Such as no less than .025 or .030, or pressures no more than 5000psi or 8000psi? I've often wondered where these figures come from and not seen a clear explanation, often its " what is used in England" but what I've seen before it what you published .

[Drew Hause]

Bruce: In the words of Will Rogers "All I know is just what I read in the papers (and on the internet), and that's an alibi for my ignorance."

I'm a bit stunned regarding the .075" recommendation just past the forcing cones

My NON-EXPERT opinion: It's a lot easier to give pressure recommendations since that information is what shell makers give, when we all know, when using shells for which the gun was originally intended, IN UNALTERED AND INTACT barrels, the primary issue is recoil and the effect thereof on both lock up and the 100 year old wood.

Since the mid-1890s the guns were designed to be used with Nitro Powder



Remington Model 1889 "For Nitro Powder"



And we know the old boys were using some real boomers

Jan. 2 1897
http://www.la84foundation.org/Sports.../SL2815017.pdf
Charles Grimm defeats Doc Carver in Chicago for the “Cast Iron Metal”
Grimm used a 12-bore L.C. Smith gun, 7 3/4 pounds, 3 3/4 drams Schultze, 1 1/4 ounce No. 7 shot, in U.M.C. Trap shell.
Carver used a 12-bore Cashmore gun, 8 pounds weight, 4 drams of Carver powder, 1 1/4 No. 7 shot, in U.M.C. Trap shell.

However, very few of us can know what sort of abuse our vintage guns have been subjected to over the last 100 years, the wood is now 100 years old and may well be oil soaked, so prudence might suggest using a Benelli SBE for 3" 1 3/4 oz Fiocchi Golden Pheasant loads like most of the low life philistines with whom I hunt S. Dakota & Kansas pheasants

[Drew Hause]

Additional commentary regarding the 1891 Birmingham Proof House Trial in Frederick Toms' Sporting Guns and Gunpowder, 1896

'Experiments On the Strength of Gunbarrels' starting on p.9
http://books.google.com/books?id=inQ...AJ&pg=PA16&lpg


"These experiments serve to show what a very large margin of strength there is in a good gun barrel, when ordinary charges are used. They also tend to prove that the brazing process (if properly carried out) does not injure the metal to any appreciable extent. It has frequently been alleged, by opponents of the proof test, that, although the barrels may pass through the proof without any apparent injury, yet the large charge strains the metal to such an extent that the barrels are likely to burst afterwards when used with ordinary charges. The fallacy of this argument appears obvious when the fact is taken into consideration that the barrels which gave way earliest under these tests had withstood the strains of nearly thirty successive trials, the first of which was rather more severe than the definitive proof charge, and the average of the whole was about four times as great as the regulation proof; while the steel barrels were tested forty times, with charges averaging nearly five times as much as the ordinary proof-charge.
Taking the cumulative grain test, as calculated in the Birmingham experiments, the strains undergone by each of the two steel barrels were rather over 110 times as great as that of the definitive proof test; and those of the Damascus were rather over 120 times the definitive proof in the case of the barrel that had undergone the brazing process, and nearly 130 times in the barrel that were not brazed. So that, although the steel barrels showed the greater amount of endurance, the strength of the Damascus was so much in excess of all ordinary requirements that no fear need be felt of their giving way when the work is properly done."

https://docs.google.com/document/d/1...EK8OtPYVA/edit

[Bruce Day]

Regardless we still get people asking here how they can get black powder loads so they can shoot their 1895 Parker damascus and we still get forum participants telling others to keep pressure "low". Of course what they really mean is low recoil for weak stocks but some stocks aren't weak at all. And some tell others to stay under 6000 or 8000psi because that is what damascus guns were designed for , with no authority cited.

Like you I do not feel that these super duper heavy loads are needed, but my point is that these old Parkers are strong guns and built to take some stout loads, then and now.