Monty: This is probably the best
extremely short version of methodology.
Sporting Guns and Gunpowders: Comprising a Selection from Reports of Experiments, and Other Articles Published in The "Field" Newspaper, Relative to Fire Arms and Explosives Fredrick Toms 1897
From The Field Jan. 15, 1896 Vol 91, p. 91
http://books.google.com/books?id=inQCAAAAYAAJ&pg=PA335&lpgA. - Damascus metal is a mechanical mixture of steel and iron.
B. - This mixture is affected in the following way: A number of small thin sheets of iron and steel (alternees), being placed alternately (faggotted or piled), are firmly wired or boxed together (forming the lopin or billet), heated in a furnace, and welded into a solid mass.
C. – The mass is then rolled out into long thin square bars or rods.
D. – The rods are then cut up into convenient pieces.
E. – Each piece is then heated and placed in a machine, in which one end of the piece is fixed, and the piece is rotated from the other end – the result being that the piece is twisted or corkscrewed very finely.
F. – The rods are rolled of various thicknesses, according to the number of rods in the particular barrels to be made. The finer the barrels are required, the smaller is the diameter of the rods, and the greater the number of rods required for a barrel.
G. – Two, three, four, or six rods are then taken, and are heated and welded together at the sides. Thus is made a flat strip, a little more than two, three, four, or six times wider than a single rod.
H. – Damascus barrels are made usually in two parts, fore part and back part, the back part being made of thicker metal than the fore part.
I. – This is done to avoid having to roll the strip taper from end to end, and to enable the welder to “jump” the barrel more powerfully than he would be able to “jump” a full length barrel.
J. – The strip is heated and rolled into a ribbon (ribband).
K. – This ribbon is cut into convenient lengths, one length sufficient for a fore part or back part, as the case may be.
L. – The ribbon is then (either with or without being heated) twisted round a round rod (mandrel) in a machine, and thus formed into a spiral tube.
M. – The spiral tube is then heated and welded by “jumping” the edges of the spiral together and hammering round the sides. This process is generally effected thus: an iron rod is inserted into one end of the spiral, and spiral placed in furnace, and when heated sufficiently, the welder withdraws the spiral from the furnace by means of the rod, and places it horizontally under a specially-made trip hammers, and “jumps” it hard vertically on an iron block let into the hearth floor, in order to force the edges of the spiral together. The hammering and “jumping” are repeated alternately as many times as required. The spiral is thus made into a rough tube. The tilt-hammer is not always employed; hand-made barrels being made by a welder and one or two strikers using welding hand-hammers.
N. – The two tubes, fore part and back part, are then heated at their joining ends and welded into one, and they then form a finished rough tube.
O. – It will be seen that
(1) The essential factor of Damascus is steel.
(2) That the various processes are effected with the object of interlacing the fibres of the metal and directed their length round the barrel instead of in a line with the rest of the barrel; so that, should the barrel burst, the fracture may follow the direction of the fibres and be impeded also by the interlacing of the fibres and the two metals, instead of being from end to end of the barrel, as it might be in case the fibres of metal run in straight line with the length of the barrel.
(3) A Damascus barrel is heated many times.
(4) The welding surfaces (a) of the thin plates, (b) of the twisted rods, (c) of the spiral, (d) of the two tubes, back part and fore part, into one.
(5) In each of these processes parts of the tube are liable to be over-heated and the steel in them then damaged.
(6) In each of these processes small imperfections in the welding are possible and most often occur. Those defects are often invisible til the barrel is finished or nearly finished, and, although the barrel may be perfectly safe, they are unwelcome eyesores to both buyer and seller of a gun.
Much more here
https://docs.google.com/document/d/1xylidcizmxlYC66XHUDLpQFtU6gi9WyXSkTayKKWCXc/edit 
