Woodcut image of gun barrel production and tools. From W.W. Greener "The Gun and Its Development" 8th edition, 1907 p. 211 'Gun-making In Bygone Days' "The method of making barrels prior to the introduction of Damascus iron from the East was to forge them from plates or strips of iron—this iron manufactured from old horse-shoe nails—not perhaps so much because of the virtue in the metal as from the fact that the nail forgers were the particular smiths who made the gun barrels. The method of the Spanish forgers was to weld a number of nails into a short strip, which strip was curled into a cylinder, six inches or so in length, and the edges of the strip, instead of overlapping slightly, made a complete turn, so that each barrel was practically double throughout. The cylinders when welded were pieced together end to end, until a barrel of the required length was produced. The cylinders are so forged that the grain of the iron, instead of running from end to end of the barrel, is disposed circularly, following the round of the barrel in such manner as to give the effect of a twist barrel. The advantages claimed for this method of manufacture were that the metal by being forged in smaller portions is better wrought and purified in the event of any defect being discovered in any one of the pieces after being formed into a cylinder, that cylinder could be rejected and a perfect one substituted by proportioning the thickness of each part to the part of the barrel in which it was to be placed very little filing of the barrel is necessary."