Hammer forged into a barrel

'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 "Field" Jan. 15, 1896 Vol 91, p. 91 - "The spiral tube is 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."