doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Damascus Pitting

What does some pitting in Damascus barrels that have adequate barrel thickness mean to the ability to shoot light loads (like RST) through them? What further testing needs to be done?

That's a timely question for me. I've had a circa 1887 W&C Scott medium quality hammergun for several years. I bought it cheap because although the damascus barrels and the rest of the gun looked pretty good from the outside, the bores were badly pitted. There is no indication to me that the bores have ever been honed to clean up the pitting.

I've been shooting it with Polywad 2.5" vintager shells on the theory that it ain't blowed up yet and removing metal from the bores to clean up the pits was not going to improve the barrel strength. Lately though, I've been concerned about just how deep those pits are. I am also worried that although I've kept the bores as clean as possible, the cleanup is always a problem and I'm not sure I've "killed" all the rust at the bottom of the pitting.

Anyhow, (coincidentally) today before the appearance of this thread, I shipped the barrels off to Steve Bertram (SKB) to seek his opinion on the feasability of back boring out the pits, adjusting the chokes to the new bore diameter, and leaving enough minimum barrel thickness to keep shooting the gun. I'd like to hear the opinions of others on this topic...Geo

I am a CHICKEN and I use full length Briley tube of a smaller gauge.
Mike

I'll start with my disclaimer...

I in no way recommend others to do what I do in shooting pitted or otherwise 'questionable' Damascus barrels.

I have read in several venues that as long as the first 10" - 12" or so (from the breech) is sound and has sufficient wall thickness, regardless of moderate pitting, and the rest of the bore and barrel wall thickness is in good condition, it should be safe to shoot.

I have shot every Damascus gun I have owned with appropriate loads depending on my evaluation of the barrels - that is to say, I shoot RST exclusively these days but had shot AA's quite a lot before. I think the accepted minimum wall thickness of a 12 gauge barrel is .0025" for the forward 2/3 of the barrels tapering thicker to the breech to be nothing less than .0090" at the front of the chamber where 'forcing cone' begins.
I have never had a single problem or issue and I never expect to because I don't take chances. And some of my Damascus guns are pretty well pitted in the first 1/3 (from the breech).

I too would like to see some definitive work done on this. However, empirically I think it's most likely individual pits don't significantly weaken the tubes if they don't cover a large area and are a moderate distance from the breech. (Go ahead and throw rocks at me). I am reminded of muzzleloading barrels that have pits completely penetrating the tube and make little puffs to the side when the gun is fired. On the subject of honing out barrels to remove pits I have come to the opinion that a barrels integrity is much more likely to be compromised when the entire tube is thinned. Of course the bores are much more attractive when they're all shiny and smooth but the strength lost is just too much for me to be comfortable.

Skeettx, I shoot too much with you--the ONLY reason you use Briley tubes is you're too cheap to buy a real subgauge shotgun

Perhaps this is a silly question, but would a small hole in a barrel necessarily spell an impending explosion? I ask because I am reminded of my sporting clays Browning Citori which has a dozen or so holes in its ported barrels, which obviously hasn't caused it to burst even though I've fired thousands of 3" steel magnum duck loads through it over the past 20 years.

A barrel is only as strong as it's weakest point.

Pits don't heal.

Continued shooting with deep pits can forge (stretch) the steel much like ring bulge caused by steel shot in old barrels. That is one of the reasons they must be honed out before re-proof.

Catastrophic failures are more likely to occur in the first 12" of a barrel as this is where pressure builds/peaks.

YMMV

I am of the mind of DAM16SXS and Joe. I've begun using Kroil if there is any pitting in the bore under the theory that it will "creep" into the pits and arrest further degradation. And, of course, I shoot low pressure, light loads. I also clean the gun after each shooting session and inspect the barrels (damascus or otherwise).

Phil.

Couple years back I was looking at gun that Elephant & Castle had listed on the internet....this "English trained gunsmith" on the phone told me he could measure the depth of the pits....I guess he figured that because I was calling from Tennessee that his English accent would hypnotize me into believing his line of bull.

Pits are like a cavity in a tooth...lining them with lead, plastic fowling or powder soot ain't going to make them go away or stop growing.

Shooting: Its Appliances; Practice; and Purpose
James Dalziel Dougall 1875
http://books.google.com/books?id=-ToCAAAAQAAJ&pg=PA25&dq=damascus+barrels&lr=#PPA24,M1

There are various kinds of flaws in barrels, such as "cracks," "sand-holes," and what are technically termed "grays." The first two are comparatively rare, but the last is the great annoyance of the barrel-forger and gun- maker; and, in fact, may be said to exist more or less in all barrels. They are those little specks in the iron which may be seen more readily after a gun has been used, from the rust showing more upon them than upon the smoother surface. In themselves, unless very numerous, "grays" lead to no insecurity in the barrels, and are not real flaws ; but the freer barrels can be made from them the better, as, unless when kept clean and well-oiled, they may in course of a long time deteriorate the barrel. As a rule they cannot be detected while the work is in progress, and only make their appearance on the barrels being browned. Conversely, strange as it may appear, most frequently they become less apparent in course of time, and on the barrels requiring to be browned a second time, disappear altogether. The reason why the first browning causes them to appear is that the infinitesimal quantity of oil they contain neutralizes the chemicals, and the mark is then for the first time made visible. The reason why they eventually disappear is their extreme shallowness. The very finest of barrels may therefore, and often have been, rashly condemned by sportsmen for harmless spots which no foresight could prevent. Were they actual flaws, they would appear during the process of filing.
The "sand-hole" is a thorough flaw; and if the barrel stand the proof at all when it exists of any size, still it cannot be quite safe, as the hole will often run in a tortuous direction for a considerable length under the surface, being, as its name imports, full of fine sand, or probably of the powder used as a flux to promote complete adhesion in welding the barrel, which has adhered to the iron, and been closed upon in the act of forging. The Damascus barrels, in contradistinction to "laminated steel," I have always found in my experience the most free from "sand- holes." Indeed of late years I have not known an instance of this flaw, through using Damascus barrels in preference to all others. Many an annoying instance I had in the days when "laminated steel" was puffed up, and when, after a gun was nearly finished, a "sand-hole" would be discovered, into which I could insert a piece of fine flattened wire and pass it half-way round the barrel between the laminae.
The "crack" is the worst of all flaws. This is a separation of the fibres of the iron from overstraining of the twist; and consequently every discharge of the gun must, by the expansion of the metal, more or less widen the crack, until it run right round the barrel. The same "solution of continuity" may also exist from imperfect forging, and the same result takes place. The author has repeatedly taken old double barrels asunder, with a crack in one of them so lengthened through time that the barrel was nearly separated into two parts. When this crack runs round the barrel the danger of bursting is exceedingly remote; but should it have a longitudinal direction, or if there be two near to each other, the danger is much increased, and, sooner or later, the barrel will give way. The longitudinal crack almost never occurs; and all the varieties of Damascus barrels are the most free from this kind of flaw. A hole right through a barrel would be much more safe than any kind of crack; and, in point of fact, many barrels are safely used for years with a small hole right through them. A crack may at once be detected by suspending the barrels, and striking them with a piece of wood, when, if faulty, they will not emit the clear, ringing sound they otherwise do.
The inside should be as bright as a mirror, and free from flaws. Slight marks or rings, left by the boring bit, can hardly be avoided, and may be found in the best barrels; but there should be no hole (pit) likely to retain dirt or damp of any kind, which can corrode the iron.
Since the introduction of breech-loaders these slight marks form a frequent subject of remark. The tube, being open, is glanced through, and the presence of such a mark is detected, whereas with a muzzle-loader this might never have occurred. Timid sportsmen fancy there is danger where none exists. In the first place, writing of course of these unavoidable marks only, no good gunsmith would permit any barrel with a real flaw to leave his hands. His final loss would be greater than his first. But besides that, in the tentative process of making a gun shoot well, he is bound by necessity to leave the barrel as it is the moment he has developed its shooting powers to a recognized standard. Hence he is debarred from polishing out any mark or discoloration for the mere sake of appearances. In breech-loaders the master-gunsmith enjoys the same opportunities to detect flaws as the sportsman, who may rest assured that the confidence put in the good faith and judgment of the former is not misplaced. The same minute marks existed in muzzle-loaders, and were known to do so by all gun-makers and by most experienced sportsmen, yet no one thought of challenging them; they were taken as a matter of course. The facility of looking through the barrels of breech-loaders has caused these utterly harmless marks of boring to be considered something new and improper. The spots are infinitesimal in size or depth, and are only visible through contrast with the bright polish of the general tube. The barrel never deteriorates with time through their presence.
Good barrels will often, when subjected to the same circumstances which would burst an inferior article, bulge, or swell out, like a glass tube heated at one part and blown into. When the bulge is not very large it may be partly hammered down, but no barrel so treated can be called truly safe, until subjected to a fresh "proof."


Making the decision to use any firearm involves a calculated risk. None of us can answer Dr Bob's question; and apparently there is no commercial/scientific technique to assess pattern welded barrel integrity. Dr Bob can run an endoscope down the bore and get a lot better look than the rest of us
As said before, judging the quality of pattern welded barrels is based on the quality of the gun. "Belgium Laminated Steel" (Twist) barrels on a JABC are not of the same quality as the barrels used on a high grade Lefever.
My concern is that deep pits will dissect into a weld and lead to barrel fracture. It took quite a bit for Sherman Bell to rupture poor condition barrels, and none 'exploded.'
To diminish the risk, one might have H.P. White Laboratory, Inc. in Maryland proof their barrel. I have no experience (anyone here?) Per Shooting Sportsman March/April 08' it ran $420.
www.hpwhite.com 410-838-6550