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Thread: Shotgun barrels and metallurgy
06-22-2010, 06:07 AM #1Senior Member
- Join Date
- Dec 1969
- southwest Virginia
Shotgun barrels and metallurgy
Not sure where this should go so I've cross-posted it to the Commercial and Sporting Arms forum...
I see a number of older shotguns listed with Damascus steel barrels, barrels made of "twist steel", "fluid steel", "armory steel", etc... I know what a Damascus barrel is, but what are the others? What's the difference between them? Any to avoid/any better than the others? Are any safe?
For instance, can I safely shoot modern low brass or field loads out of a 16 gauge with fluid steel barrels, or should I roll my own black powder loads, for example?
06-22-2010, 09:36 PM #2
You are aware that the height of the brass no longer determines the pressure in shotgun shells. Low and high are generally the same pressure anymore.Bear 45/70
Gimp racing Team
"God must love stupid people. He made SO many."
06-23-2010, 07:44 AM #3
Twist is just an earlier form of damascus without the braiding. When damascus came into fashion it was relegated to cheaper and thus probably weaker barrels. But in all cases the quality of damascus/twist depends on the quality of the maker. There are also various other names for this welded up construction and I'll post links when I get home in a couple of days.
There are also many trade names for barrel steel, and most mean no more than do the brand names of toothpaste. For that 16 guage,it depends on the make and age and loads it was designed and proofed for and you should refer to the various make collector's websites or the BBS at Doubleguns.com Many old shotguns were built around lower pressure loads and/or shorter shells before lengths were standardized. To this day many British 12 ga. are made very light for short shells. You must have the chamber of any pre 1932 American shotgun measured unless the shell length is stamped on the barrel. Just the ability to chamber a 2 3/4 in means nothing as the chambers have extra length for the crimp to unfold and stretch.I swear by Jupiter Optimus Maximus .... in the army of the consul Lucius Quinctius Cincinnatus and for 10 miles around it I will not steal anything worth more than a sestertius in any one day.
06-26-2010, 06:43 PM #4
From a Brit forum, the Internet Gun Club:
From: Greater London, United Kingdom
Posted: 2005-05-03 13:15
This is a section from my book - I thought you might find it interesting.
Prior to the development (in the 1880s) of the technology to produce steel barrel tubes in one piece, barrels had been made by a process of hammer welding different grades of iron and steel around a mandrel. The resulting, figured, barrels are generally referred to as ‘Damascus’ by modern writers. However, ‘Damascus’ barrels were made in a wide variety of grades and the manufacturing process varied accordingly. Here are some common terms encountered when reading contemporary writers, about types of Damascus barrel and what they refer to:
This was made from best quality steel scrap mixed with some charcoal iron and worked under a forge hammer repeatedly until the close and even grain desired was achieved. The metal was then rolled out and shaped into a tube in the conventional manner. Greener praised the practical, hardwearing qualities of laminated steel. Unfortunately, from an aesthetic viewpoint, it lacked the intricate pattern of other forms of Damascus barrel.
This was usually made by heating old files, quenching the red-hot metal to make it brittle and then pounding it into very small pieces. This was added to a quantity of nail stubs from horse-shoe nails. The mixture was heated in a furnace to fuse the component parts. The metal was then hammered into rods and twisted and welded into tubes in the usual manner.
This was a cheap variety of barrel material also referred to as ‘Twopenny’ or ‘Wednesbury Skelp’. The iron used was of lower quality scrap but if well forged and hammered could be serviceable. Skelp tubes were not used for good quality guns.
A poor quality steel barrel was formed by welding along the length and then wrapping a thin Damascus layer over the top to deceive the buyer (or gunmaker) into believing the barrel to be a higher quality one of Damascus construction.
This type of Belgian tube was very well figured and free from ‘greys’ and became popular with some British gun makers in the1880s. It looked attractive but lacked the toughness of British Laminated Steel.
English Steel Damascus
This was composed of steel and iron in six-parts-to-four proportions. Tubes made with higher steel content, usually eight-parts to two-and-a-half of iron were termed ‘Silver Steel Damascus’. In either case, the best barrels used three or more twisted rods of metal and were well figured and tough.
There was an interesting Birmingham proof house experiment to discover the relative strengths of the available barrel tubes carried out in 1888. The test-barrels, equal in size and wall thickness, were each in turn loaded with a charge of powder and shot and fired. The shot and powder charge was increased until a failure became apparent in the material (a bulge, a split, a break etc), at which point the result was recorded and the barrel eliminated from the competition. The test was a kind of ‘last man standing’ contest and the results were surprising:
1st English three-rod machine-forged Laminated Steel.
2nd Whitworth Fluid-compressed Steel (by far the most expensive of the three).
3rd English two-stripe Damascus.
Remember – there will be no more Damascus, ever. Nobody has the skills to make Damascus anymore so a fine pair of Damascus barrels on a gun should be appreciated for the excellence and rarity they represent. As a caveat to the last statement, it has come to my attention that some stocks of Belgian Damascus barrel tubes of high quality have been discovered in storage and made available by Peter Dyson in the UK. There are also rumours of some experiments in Sweden with modern production of Damascus-style tubes. Perhaps, like the return of the wild boar and the great bustard to the English countryside after years of being hunted to extinction, we shall again see some guns being produced by English makers featuring Damascus barrels.
Finally, a word of practical advice: When buying a gun with Damascus barrels, remember that it will have ‘dovetail lumps’, rather than the ‘chopper lumps’ of best steel barrels. This is no indication of inferior quality (Damascus tubes could be made in the chopper-lump style but the metal was not hard enough to stand the friction-induced wear required of lumps) but the join needs to be checked for integrity as part of the overall evaluation of soundness. Early steel barrels were dovetailed in the manner of Damascus, but this method was superseded by the forging of the lumps as integral parts of the tube, in the now commonly used ‘chopper lump’ method employed on best guns.
Note from jjk308: All Damascus, Laminated Steel and Skelp is twist. Prior to about 1800 strips of iron were used, then wires or strips of iron and some steel, then about 60% steel, braided with iron to form the Damascus pattern. The strands or strips were wrapped around a mandrel and hammer welded, then the mandrel pounded out and the barrel bored true, straightened and finished. This is "the usual manner" and aside from the not completely satisfactory attempts to lap weld mass produced barrels from heavy iron or steel sheet was the way most barrels of shotguns and rifles were built prior to the development of drawn steel barrels.
By the time of the late 1800's - when the information above dates from - Skelp was considered cheap and weak. But until Damascus became popular top quality skelp made with lots of steel was as strong as laminated steel.
"sham-dam" usually didn't have any damascus layer but just had the damascus pattern etched on with acid.I swear by Jupiter Optimus Maximus .... in the army of the consul Lucius Quinctius Cincinnatus and for 10 miles around it I will not steal anything worth more than a sestertius in any one day.
06-26-2010, 07:41 PM #5
From my excavating the other day, "fluid steel" barrels are not a "twist-type" barrel. They are a solid steel bar forging, bored out, and acid etched to generate the swirly "fluid" pattern on the outside of the barrel.
06-28-2010, 07:47 AM #6
Some may have been but most "fluid steel" barrels i've seen are smooth, unetched. The term comes from the Whitworth "Fluid Compressed Steel" process of compressing a steel casting while still molten to eliminate blow holes, then cutting off the exterior surfaces to insure the steel ingot has no voids. Then the barrels are manufactured by any of the usual methods of forging, drawing and/or drilling.I swear by Jupiter Optimus Maximus .... in the army of the consul Lucius Quinctius Cincinnatus and for 10 miles around it I will not steal anything worth more than a sestertius in any one day.
06-30-2010, 07:08 PM #7
Ruger and a few other shotgun Mfg's use the GFM cold forging machines for most of their barrels, shotgun and rifles. Blanks are low sulphur steel which look like short 1" pipes~16" long. After forging the OD has the long slow twist radial lines seen on the heavy barrel Ruger 10-22 rifles. OD is turned to size,ID is ready to go, after heat treating and trimming to length. Quick process V the conventional process(s).
07-01-2010, 08:02 AM #8
Forging around a rifled mandrel should be the optimum way to make an accurate rifle as you can forge in a .001 in. or so taper to the muzzle that improves accuracy. But apparently some manufacturers use the same mandrels for too long, and the wear results in some inaccurate rifles and customer complaints, plus the usual old timer tales about the superiority of cut rifling and how crummy all this new fangled stuff is.
07-01-2010, 05:16 PM #9
True, the mandrels "wear" out, more so for the rifle and pistol barrels as the rifling is in relief. Back in 78-79 when Ruger was looking at their first GFM machine, quite a few were run off for other MFG's in .308 as well as .223. I do recall the then head process engineer for Marlin telling us that" the last 6 inches of any barrel is the most important". Many old timers swear by button rifling as do cut. OTOH ,when one views a hammer forged barrel's chamber and rifling through a microscope, they see the advantage.
07-01-2010, 06:36 PM #10
Is it safe to shoot a laminated steel barreled gun with just field loads?
07-06-2010, 11:35 AM #11Senior Member
- Join Date
- Dec 1969
- S.E. Arizona
Makers of modern ammunition still print a warning on all their smokeless shotshells that such are NOT safe to use in Damascus or twist steel barrels. And for good reason.
It is never safe to asume that such a barrel, no matter whether it was made by a top maker or otherwise, is safe to shoot at all - it was originally a mass of welds from end-to-end, and hasn't improved with age, even if it appears sound to the closest inspection. There is simply no way to know whether it is (or ever was) fully sound, and no one should ever shoot such a barrel with any misplaced confidence that it is perfectly safe to do so.
I have, do , and will continue to shoot such barrels, but only with blackpowder loads, or equivalent loads of one of the current BP substitutes - and I'm not fooling myself that nothing can go wrong: I've inspected too many wrecks to believe ANY such barrel is perfectly safe, and the fact that many of them have been shot for varying periods of time with smokeless shells (or have even withstood smokeless proof) only demonstrates that they haven't failed YET.
Do what you think best, but weigh the benefits carefully against the known, but unquantifiable, risk.
PRD1 - mhb - Mike