Authored By Dan Alex (Updated: 5/9/2016):
Mauserwerke engineers began redeveloping the MG34 as early as 1940. By now, the Germans were at total war with neighbors and in far-off places like North Africa so all of her warring services (land, sea, and air) required the MG34 but even five full factories committed to its production could not eliminate the shortages of the excellent machine gun. Experience in the manufacturing of the MP40 submachine gun - a streamlined production version of the MP38 SMG - showed Mauser just how to approach a more simplified production model and this small window of opportunity also allowed its engineers time to incorporate several design changes to the internal workings of the new gun. Ideas were taken from original Czech and Polish offerings while Mauser personnel also instituted their own. The result became the MG39/41 which ultimately emerged in its finalized form as the MG42 - known by its long-form name of "Maschinengewehr Modell 42". As its designation would suggest, service entry officially occurred in 1942. Design of the gun is attributed to German engineer Werner Gruner (1904-1995).
Amazingly, Mauser found the perfected balance of cost-cutting while retaining a robust end-product. This meant that the MG42 could be made available in number within cost and not falter mechanically under the stresses of battlefield abuse. Indeed, a single MG42 weapon could be completed in half the time it took to forge an M34 system. Sheet metal stamping was used for the barrel jacket and at the receiver and reduced reliance on machining and skilled labor added more production value in the long run. The quick-barrel change facility of the MG34 was retained - a trained operator able to complete the process in under five minutes. A barrel was recommended changed every 250 rounds fired so as to keep it from overheating. Unlike the former model, which fed from 50-round belts, a 50-round drum, or a 75-round twin saddle drum, the MG42 relied solely on 50-round belts or 50-round drum within an all-new feed mechanism. It also kept the ubiquitous 7.92x57mm Mauser German rifle round as its chambering and also used the short-recoil gas function with added pressure from an integral muzzle booster. The original rotating bolt function was dropped, however, as it was now replaced by a Polish-inspired method using a recoil-operated, roller-locked action. Sighting was through the typical iron arrangement though optics could be fitted as needed.
Production of the gun from Mauserwerke AG, Wilhelm-Gustloff-Stiftung, and Steyr-Daimler-Puch reached 423,600 units by war's end (some sources go as high as 750,000 examples). Production peaked in 1944 with 211,806 units completed.