The barrel is made from aluminium EN AW-1050A according to UNI EN 573-3 of a purity equal to or greater than 99,5% and electrolytical copper Cu-ETP CW004A according to UNI EN 13601. The aluminium barrel is friction welded to the copper palm achieving the best possible transition between the copper palm and aluminium barrel. Barrels are capped and filled with grease to avoid oxidation of the aluminium.