Abstract: An armor-penetrating projectile comprises an outer substantially cylindrically tubular member of great length/diameter ratio and density, centered on an axis, and having an axially throughgoing bore defined by an inner surface and an axially elongated inner member of greater strength and elasticity than the outer member extending axially through the bore the full length of the outer member and having an outer surface in tight radial contact with the inner surface of the outer member at at least a plurality of annular locations spaced along the axis. This inner member can be a bundle of wires that is inserted through the bore after the outer member has been expanded by heat, then twisted and longitudinally prestressed to lock tightly in the outer member.