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How are barrels regulated?

If bending is involved, how is the strain on the welds relieved?

Hi,
I don't think modern barrels have welds. The barrels are bored, I believe. On some of the Parkers I have owned, I thought I could see that one barrel was "Englished", or bent slightly to parallel the left one by looking through it. However, I asked Oscar Gaddy about this and he had never noticed it.

Bm,
Barrels on most production sxs guns were/are assembled to established dimensions of convergence. That includes some of the pretty pricey stuff.

How the developed the "established dimensions" is usually thru shooting. Then those dimensions would be applied to production guns by either providing assembly tooling or by simply providing the assembler of the barrels with the dimensions.

The 'how' of actually assembling and solding barrels/ribs will really surprise you. Drew has a website dedicated to gun knowledge that has an article I put together on the traditional method of bailing wire and spacers and pro gunsmith has an article where he made an assembly fixture. Hopefully Drew will drop in and provide the link to his site.

PS
Jim is correct, barrels are generally bored from solid bar. An alternate method is to drill a short fat bar and hammer forge it to the nearly final shape in a special barrel making hammer forge that looks like a big lathe.

Really old methods were to forge weld a series of strips of metal over a mandrel. This was the method for "twist steel" and "damascus" barrel making. Drew also has articles on this as well as PeteM on his website.

By welds I meant the seams between the barrels and the ribs.

Bending the two barrel from one side to the other would stretch the near barrel and compress the far barrel, putting strain on the seams

BM,
The "seams" between the ribs and barrels are generally soft soldered with 60/40 tin/lead solder. Alternatively, they have been soldered or brazed using various higher melting temp mixtures containing either silver or bronze or both.

The barrels are simply pulled together to get the predetermined dimensional convergence (angled together) based on earlier shooting experience. Spacers are put inbetween the barrels at a few locations where the bailing wire will be used to bind the ribs and barrels together to prevent them from bending the barrels inward excessively when the bailing wire is twisted up tight. Then the whole mess is heated with a torch to solder everything together.

Here's the link to the web article.
http://www.picturetrail.com/sfx/album/view/18691676

Bushmaster,

I know you are asking about the ribs, etc. These are some pictures of earlier methods of barrel making.

Here skelp is hammer forged around a mandrel.




This is from a patent for a rolling mill that can create barrels from sheet stock.


This is damascus being wrapped around a mandrel


Very few shotguns are individually adjusted for poi. Holland & Holland has an excellent video that shows them hand adjusting barrels while at a patterning board. This process is reserved for only the very best grade of guns. Early on barrels, made from solid stock, were being brazed.
http://www.gunmakersrow.co.uk/

Pete

The one double rifle I saw being regulated was done with the ribs off the gun.

I believe the H&H DVD shows a shotgun being shot for regulating without the ribs. But some here and maybe it was Kirk Merrington (I could be wrong on that) that told me the ribs will influence the POI and should be installed and removed for regulating.

Chuck, the shotgun in the H&H video was complete with ribs in place. The only "regulating" done was for pattern only. They did show the POI regulating of a double rifle and that did involve loosening the rib and adjusting the barrel wedge at the muzzle. I'm inclined to go with what Jack Rowe recently told me: shotgun barrels were not regulated for POI unless something was badly amiss. He pointed out how much POI could move by just simply varying the loads. I loved his closing comment, "my goodness, it's a shotgun.....just shoot it!"

Joe,
It's been a yr or more since I watched the video and now it's been with a friend for most of that time. I need to get it back from him.

I understand what Jack was trying to say, but once you've taken a set of barrels appart and are putting them back together, you get really concerned about regulating them for not only the convergence but the elevation relative to each other.

When I did that 28g conversion on a 20g LC, the convergence was way off when the muzzles came together, then the POI relative elevation was also somewhat askew even though carefully aligned on the outside of the barrels.