Abstract: A pierced metal blank having an annular cross-section with one end closed and the other end open for use in the manufacture of seamless tubes has a bore with portions of different diameters, the portion of larger diameter, which is adjacent the open end of the blank has a wall thickness which is less than that of the portion of smaller diameter which is adjacent the closed end of the blank. Preferably there is a conical transition between the two portions of different diameters. The blank is preferably made from a metal billet of square cross-section in a substantially cylindrical piercing mould by piercing the billet within the mould by means of a stepped mandrel which presses the material of the square billet outwards into contact with the cylindrical wall of the mould.