This is a scarce example of a WWII German aircraft mounted ball/turret machine gun as manufactured by the Heinrich Krieghoff Company. This has to be one of the scarcest machine guns due to the fact that so few were actually bought back after WWII and registered. This type of machine gun replaced the older drum/magazine-fed MG 15s and was used in the flex mounted positions in the nose, side and top turret type mounting positions in the medium and heavy Luftwaffe bombers such as the Heinkel HE-111, Stukas and Messerschmidt 110 fighter/bombers. If you recall the epic movie The Battle For Britain, which was a key air battle in 1940 between the British RAF and the German Luftwaffe. In that movie many times they showed the nose and top gunners in Heinkel HE-111 Bombers, firing at Spitfires, using this same exact type of machine gun. The MG 81 was developed in 1938/1939 by the Mauser factory as a derivative of their successful MG 34 infantry machine gun. It was in production from 1940 to 1945. These MGs are totally unique weapon on to themselves in that they have no buttstock since they were aircraft mounted, they are a belt feed MG, they have a light weight barrel with a perforated barrel jacket designed for rapid cooling during firing (while in flight) and they used a set of unique antiaircraft sights mounted on the barrel jacket. The sights are a large fixed post front sight with a very large aiming circle with a cross hair for the rear sight. As noted they are a left hand belt feed and they have no traditional cocking handle, instead they have a large recoil spring mounted on the underside of the receiver, with a cocking ring (in lieu of a cocking handle) on the rear of the receiver. They could be employed in a ground mount version if the aircraft had crash landed with the convertible buttstock assembly usually stored in the plane. The top cover is stamped "MG 81/26060/fzs/R" which is flanked by two Luftwaffe Eagle/2 acceptance proofs from the eh Krieghoff factory. The left rear side of the receiver is also stamped with "26060/Eagle/2" proofs. The top rear are of the barrel just behind the mounting block is also marked "26060/Mantel n.A." Many of the other parts also have the correct "Eagle/2" Luftwaffe proofs from the Krieghoff factory. It still retains its original wooden pistol grip and the outside of the barrel jacket has been painted black. The gun has been rendered inoperable by two plug welds on each side of the receiver, that go into the sides of the bolt. It has its original WWII green phosphate finish on the metal parts with a slightly darker color on the trigger housing.