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
