Abstract: A method of fabricating a lighter composite master brake cylinder is disclosed along with the resulting product. A seamless steel tube of critical thickness, closed at one end, and treated by acid etching on its exterior, is oriented vertically within a mold cavity. The tube is pretreated to contain critically dimensioned punched and coined openings for brake fluid filling and fluid delivery. Openings in the cast body are defined by pin cores aligned with the tube openings and are dimensioned to separate the edge of the tube openings from the cast opening. The tube is supported by a plug extending snuggly into the interior of said tube, said plug being joined at one end to the die walls; the cores are also supported by suitable attachment to the die walls.