doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Thoughts on TIG welding on a barrel

In the very early part of the 20th century, in Britain, Brearly had already "discovered" chromium increased strength and ductility in gun barrels. Haynes in the U.S. developed it around that time too. Krupp was doing the same thing (probably a big reason for their reputation of strength) likely well before the rest of them. I seem to recall reading about all the industrial espionage going on around that time. By the twenties, these alloy steels were being used pretty commonly, especially in high quality guns and military arms.

Take a look at this exerpt from Mac's Fox book. There are references directly to chrome-nickel and vanadium steels, "Chromox" etc. associated with 1911-1912 times.
http://books.google.com/books?id=cbRI_7U...eel&f=false

So, I'll stick to my statement that I don't beleive LC Smith had 1020 barrels. Heck that numbering system wasn't even around when chrome-vanadium steels came about. 1020 is muffler tubing.

I hate to comment because I�m a crappy welder but, I design welds all the time so I'll say something. I would approach this question from a different direction.

The most important factor is the stress the weld must withstand. First, make a reasonable estimation of the stress the weld will experience upon firing. Next, decide how comfortable one is with stressing a weld to that level. We will need to know the barrel wall thickness at the saw cut to estimate the stress.

For safety I would assume a high chamber pressure. Then I would consult one of those pressure drop diagrams and conservatively assume a pressure at the saw cut. Then I would calculate the resulting stress in the weld.

If the stress worked out to 5,000 psi, I wouldn�t worry about not knowing the exact metallurgy of the barrels. If the weld stress was 30,000 psi I might think differently.

Anyway, first determine how �good� the weld needs to be. Then decide on the testing and welding procedures needed for peace of mind. The barrel wall thickness is important.

One thing working for this gun is that it is a small bore so the stress equation is more favorable for a given pressure.

Chuck, going through Brophy's "Plans and Specifications", I came across a print from Hunter Arms dated Feb, 19, 29 and this print is for the barrel lug. It calls for SAE 1020 and below that shows barrels saying "steel app. 40 carbon".

They also list, chrome vanadium SAE 6150 to be used for firing pins, if unavailable use Carpenter's 5317.
Chrome vanadium, I believe is drill rod and is a lot harder than barrel steel used then.

This is getting to be interesting in trying to figure out what kind of steel low graded barrels were made of.
I described this earlier in this thread about going to a scrap yard and getting some alumium round stock. I wanted to be sure it was 6160 and asked. One of the workers got a hand held machine and held it on the piece and in a few minutes read the properties of the aluminum, the fellow then told me it was 6160. I wonder if they could do the same with a barrel or receiver.

David,
The lug being made of 1020 is not unreasonable. The stresses are low on it. Barrels are a different thing altogether.

That fella likely performed a conductivity test. It works well for identifying aluminum alloys but I 've not heard of any simple non-destructive test for steel alloys. The issue I see in welding this gun is the cracking of the weld I encountered with my sleeving project. If you don't encounter that or overcome it, it might work out.

There are damaged and blown-up L.C. Smith barrels out there. How large of a piece would one need to have analyzed by a metallurgist to determine the type of steel? I have a blown OO grade barrel, but that may be too old to say it's the same as this 20 ga.

I'm conflicted about this type of query. I really hate to see vintage collectible doubles destroyed or parted out. If this was my Grandfathers' gun and it had sentimental value, I would want to try to save it, and I would be thrilled if I could TIG it and reblue and have a near undetectable repair that allowed me to use it with the usual low pressure loads.

On the other hand, If I bought it at a poorly lit gun show and paid anywhere close to book value, I would be pretty pissed if I later examined it in bright sunlight and noticed that my new baby had a weld repair on the barrels. So while I feel that this may be do-able and probably safe (remember all those Damascus barrels with about a hundred miles of hammer welds fluxed by borax), even someone with the best of intentions may not have any control when it is sold at some point in the future.

Keith, thanks for your interest. The barrels on your OO would also be Armor steel as those on this Field Grade 20 ga.
The OO Grade, introduced in 1898 was offered with Armor Steel. This steel, I believe was made by an American Company and was in used until the end of the company in 1945. When Marlin bought them out and continued making L.C. Smiths, the Field Grade with Armor Steel barrels was still there and stayed until 1950 and again in 1968-71. I am sure changes were made in the steel but the only way to find out is to have as you said, samples for the different years of Armor Steel.

I would be glad to chip in and I'm sure there might be others also, to find out what the properties are in these barrels for future references.

David, if you determine that a 1900 OO grade would have used the same steel as this gun, and would like to test a small piece to determine content, let me know. I had everyday access to a Met Lab until about 2 months ago, but I won't have easy access again until late spring or summer. A couple of the guys I knew who worked in that Lab were gun guys who would have happily done spark, Infrared Spectroscopy, hardness testing and whatever else they do for free, or a beer at most. Government work, you know.
Maybe someone else here has similar access now at similar cost.

Keith, a 24 year difference in age and I would think the steels would be very close, maybe by now a little more carbon content as Chuck was saying.

Plus, the same weld/test could be done on a piece of yours.

Nov. 30, 1895 Sporting Life
http://www.la84foundation.org/SportsLibrary/SportingLife/1895/VOL_26_NO_10/SL2610011.pdf

"How Shot Guns Are Made and the Process Through Which They Pass Fully Explained"

The beginning of the manufacture of a gun is the barrels, and it is generally known that no barrels are made in this country except the rolled steel, which is used on the Winchester gun. All gun barrels are now imported, although an attempt was made a few years ago to produce them in this country, but with only partial success. England, Germany and Belgium supply most of the barrels, the latter country doubtless producing the larger quantity. All gun barrels, whether imported direct from the makers in Belgium, or through an importer in this country to the gun manufacturer, are received in rough tubes, which very much resemble a couple of gas pipes, but being somewhat larger at one end than at the other. These barrels or "tubes" as they are called, are merely tied together in pairs, with small wire and 40 to 50 pairs are packed in a box.

More here including Thomas Hunter's testimony regarding the Payne-Aldrich and Dingley Tariff Bills in 1912
http://docs.google.com/document/pub?id=17ixogftgITEblNUWtmFBv96ZvgjK6eFell8GsAWd-KI

Maybe, maybe not. As Drew notes above, even two guns made in the same week may have used rough barrel tubes from differing sources and materials. That's why I mentioned earlier that it would possibly be nice if you could recover the hacksaw shavings from this exact barrel. I'm sure it would be difficult or impossible to spark or hardness test steel sawdust by conventional means, but there may be other tests that could use a very small sample. I'd bet Nuclear Magnetic Resonance Spectroscopy could tell us a lot, but I have no idea where you could get that done or what it would cost. I used that method many years ago in Organic Chemistry Lab as a tool to analyze some very small samples of unknown crystals. It was something that only large universities had at the time. Still, other tests were often needed to confirm results. You don't have a buddy who works at an FBI Crime Lab or something, do you?