The rifle's integrated grenade launcher is essential for those wishing to "grenade jump" to otherwise unreachable ledges within the games. The M.75 and MA-75B can only be operated in atmosphere. Neither will work in vacuum nor in fluid. The assault rifle is first found in Marathon on the second level, Bigger Guns Nearby. In Marathon 2: Durandal, it can be found on the first level, Waterloo Waterpark.