doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Hot barrels, barrel construction, and other stuff

So, if heat is not the reason for hard-soldering then why aren't all barrels soft-soldered? My suspicion is that soft-soldering does not have the "sheer" strength (the force of acceleration and deceleration) necessary to insert and hold the barrels in a mono-block breech?

Is this true? Is there another reason for hard-soldering barrels?

Hot Blue ?

I believe Postoak has it. So they don't have to rust blue them would be my first impression. And some makers still use soft solder, for that matter. Rigby's double rifles are soft soldered, if I remember from the article on them - they have a torch at the regulating range so they can make adjustments to the barrels/ribs during the regulating process. I assume this means soft solder, but I'm not sure of it.

I can add that cyclic fatigue, tensile strength, ease and method of application, and corrosion resistance must be considered

I was told by an old English trained gunsmith that the reason soft solder was used was because of the high Tin content (96%). He said Tin had the same expansion rate as steel and that keep things from coming loose as they heated up. He recommended pure Tin if you could find it.

Mark

http://www.mbabllc.com

As for sleeving barrels with softsolders, they have plenty of shear strength for the job. Think about it. Multiply the area of the solder joint times the shear strength of the chosen solder. There are fairly small forces trying to push a tube out of a sleeving job or monoblock. Many fine guns are still built with monoblock softsoldered tubes.

I'm betting the reason lead/tin solders were chosen originally was for their ease of use in a small craftsman's shop. This not only includes the soldering process itself, but the cleanup prep for finishing as well. Try cleaning up excess braze (pick one; silver, bronze, etc.) a fillet in some thin barrel/rib area that is brazed. You'll likely mess up the tube wallthickness and be cursing before you're done.

Here's an interesting patent I bumped into by accident. "fatigue resistant" solder alloy. Hmmmm.

Title:Fatigue resistant lead-tin eutectic solder

Document Type and Number:United States Patent 5308578

Link to this page:http://www.freepatentsonline.com/5308578.html

Abstract:The fatigue resistance of lead-tin eutectic solder is increased by doping the solder with about 0.1 to 0.8 weight % of a dopant selected from cadmium, indium antimony and mixtures thereof. The doped eutectic solder exhibits increased resistance to thermally or mechanically induced cyclic stress and strain. As a result, the fatigue resistance of the solder joint is increased. Combination of dopants, such as indium and cadmium, in combined amounts of less than 0.5 weight % are especially effective in increasing the fatigue resistance of the lead-tin eutectic solder.

Chuck: Thanks for the information!

We are having a little discussion over on the 16 gauge forum about barrel construction, alignment, and soldering methods. As much of these discussions become, this one has become more academic than pragmatic.

However, another question I have has to do with how smaller Italian manufacturers make their barrels. Are they using a different process than Miroku? Who supplies the barrels for smaller Italian gun makers?

Also, when barrels are made either via hard-soldering them or soft-soldering them, how many are rejected because they are misaligned?

Thanks,

david

Chuck, I'm with you. In the 1800's what else was available for joining the barrels that was usable in a gunsmith's shop. Soft solder was about it. Brazing was not unknown but was usually a furnace procedure until the fuel-air torch was commercialized in the late 1800's. Even then, the high temps would have been difficult to manage when something like double rifle regulation was attempted.

OB

David,
Can you give me the link to the 16g forum? I'm in the middle of relaying ribs on my Parker. Maybe I can pick up a tip or two.

I recall looking for shotgun barrels yrs ago when Brownells dropped them. I found an Italian manufacturing company that specialized in contract work and parts, including barrels. I wanna say the name was Emmbi or something like that. I did see some of their guns labeled with their name on rare occasion.

As to how many barrels are rejected for misalignment, I'll say probably none on production guns since they don't seem to check them and none on custom/bespoke guns because they straigten the tubes before starting and shoot and re-regulate until right, then finish the gun (watched that on the H&H video). On production guns, I've run across a few with barrels that were bent (curved) over their length bad enough that you could see it clearly and would print POI in two different places. It was a 3200 that I owned for about a day. Another was a Grulla sxs that had the barrels clearly swept upward so much that it shot like a trap gun. It went down the road from that owner. On a production gun, I'm willing to bet few shooters ever notice misalignment.