Submachine gun, MP 40, maker "cnd" German, SN 3315n WW II. Matching lower body, upper body and barrel. Missing bolt when donated. Manufactured by C.G. Haenel Works (Waffen- u. Fahrradfabrik, late code "fxo"). FXO 042. This MP-40 has some parts made by the sub-contractor National Krupp Registrierkassen, GmbH, Berlin: "cnd" DEACTIVATED. MP40 Manufacturers and Markings There were three main companies manufacturing the MP40 for the Heeres Waffenamt (Army Armament): Erma, Steyr and Haenel. The C.G. Haenel company already ceased production in 1942. Those above mentioned prime contractors would utilize subcontractors to source some of their parts for final assembly. Those subcontractors were Merz Werke and Krupp. During the process at the subcontractor level all parts were marked with a unique letter code identifying the subcontractor. Inspectors of the Army Acceptance Organization (Heeres- abnahmestelle) would additionally stamp each parts for accuracy with their unique mark. Finally shipped to the prime contractor where the parts would be assembled and fitted into one unique gun, letter code markings for the prime contractor would be applied besides a serial number and lastly for final inspection Heeres Waffenamtmarks. The reason behind this time consuming process was the fact that tolerances were very tight in German machining and parts were not totally interchangeable between unique guns. The prime serial number of a gun was placed on the left side of the receiver tube and the end cap of the trigger frame together with the year code (e.g. "40" for 1940) A total of 869,792 MP40s were produced. MP 40 submachine guns are open-bolt, blowback-operated automatic arms. Fully automatic fire was the only setting, but the relatively low rate of fire allowed for single shots with controlled trigger pulls. The bolt features a telescoping return spring guide which serves as a pneumatic recoil buffer.