MP40 Manufacturers and Markings
There were three main companies manufacturing the MP40 for the Heeres Waffenamt (Army Armament): Erma, Steyr and Haenel. Steyr manufactured the majority of the MP40 submachine guns and production continued at the company unitl 1944. Erma who also manufactured the MP38, produced the MP40 until 1943. The 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 Waffenamt-marks. 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)
Prime Contractor Marks:
Subcontractor parts and subassembly marks:
Alpha numeric patterns were used for the serial numbers. The serial number usually consist of four digits or less and a small case letter. The first sequence of numbers start from 0001 to 9999 followed by the second sequence from 0001a to 9999a. The third sequence would end in b, the third in c and so on. Every year this sequence would repeat itself.
Above example with serial number 41662 would be an MP40 made in 1942 by Haenel using subcontractor parts from Krupp.
A total of 40,576 MP38 submachine guns were produced and 869,792 MP40s.