The M240D is an upgrade of the M240E1, primarily in the addition of an optical rail on the receiver cover. It has two possible configurations: aircraft and egress (ground). In the aircraft configuration, the M240D has a front and rear sight and a trigger group which accommodates the spade grip device, while the ground configuration involves the installation of an egress package or "infantry modification kit", which is designed to provide downed aircrew personnel with increased firepower. The egress package contains a buttstock assembly, a buffer assembly, a bipod assembly, and a conventional trigger assembly.