A casing mill having a main body with cutter bases with cutters mounted on the cutter bases. The cutter bases are moved radially by operating arms which are rotatably attached to the main body, which are in turn moved by an operating mechanism in response to fluid flow through. One or more of the operating arms are extended to form a cutout arm, which enables cutting an initial window in a casing string, from which milling can continue. The operating arms are mounted to the main body by pins, which are held in the main body by a pin retaining arrangement.