It appears I may be all wet on the Sir Joseph Whitworth Fluid Compressed Steel bar stock(carottes) being converted into tubes as Whitworth formed hollow cylinders via his unique molds with hydraulic presses.
1873 diagram showing the mold & the hydraulic compression cross-section.
It is very difficult to extract data on shotgun tubes as the market was such a very, very small portion of the overall steel making process. Steel concerns were interesting in peddling steel plating for ships and big guns for hurling 100lb cylinders of lead. And barrel makers wanted contracts on millions of implements of war. So info is scarce and has to be either inferred or deduced. Seeing a rough Sir Joseph Whitworth Fluid Compressed Steel tube would be most insightful. But when one considers the fight over the U.S. of A. tariff on "shotgun barrels, forged, rought bored" I believe we can come to a consensus that indeed Whitworth & Company was supplying rough cylinders and I think this to be the only case where a steel mixer or steel process developer provided cylinders for shotgun tubes.
So it was Baldwin Bros. & Company that was leading the charge on importation of Sir Joseph Whitworth Fluid Compressed Steel tubes.
Typically, it took several passes, say 15, to bore a cylinder to the desired diameter. The cutting head was well oiled and lubricated and in some cases a stream of water was employed. Wet rags were placed on the outside for a thermo effect in an effort to prevent the loss of temper. So it is possible that Purdey's mechanics bored the cylinders and employed a La meche or square head, maybe a spill with a piece of paper or leather, being some 10 to 12 inches for the final cutting. Enlargement was accomplished by the aide of a spill, an insert of wood, paper, leather - the Etelle.
Kind Regards,
Raimey
rse
