Pattern welded 'rough forged tubes' were made in 2-3 segments that were butt welded; thicker at the breech, thinner at the muzzle. The pattern is very difficult to identify when rough forged, and even harder 'in the white' after finishing but before coloring. Two tubes would be matched for pattern, wired together, and shipped in a lot of maybe 50 to the U.S. makers for finishing, joining and fitting. It is not uncommon to see a little pattern difference comparing the breech to the muzzle segments, partially related to less grinding at the breech.
Nov. 30, 1895
Sporting Life
http://www.la84foundation.org/Sports.../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.
This Colt was identified by another member with a fairly obvious pattern difference
Bro. Bruce posted this D3 previously
More examples here
http://www.picturetrail.com/sfx/album/view/18015717
and Colt Damascus here
https://docs.google.com/a/damascuskn...xa1kDegrg/edit
Mis-matched tube segments
Linear Mode
