Original Madsen Light machine gun for Sale at International Military Antiques. The Madsen was the first successful light machine gun, entering production in 1902. It saw much use, but was an unusual design – basically a fully automatic falling block action. It used a top mounted magazine offset to the left side of the receiver, allowing the sights to remain on the centerline of the gun. The Madsen was available in a wide variety of calibers, configurations, and barrel lengths.