A U.S. report on the German MG 42 machine gun in WWII, from Tactical and Technical Trends, No. 31, August 12, 1943. [DISCLAIMER: The following text is taken from the U.S. War Department publication Tactical and Technical Trends. As with all wartime intelligence information, data may be incomplete or inaccurate. No attempt has been made to update or correct the text. Any views or opinions expressed do not necessarily represent those of the website.]

MORE DETAILS OF THE GERMAN MG 42 While an account of the new model 42 dual-purpose machine gun was published in Tactical and Technical Trends, No. 20, p. 28, further details of this light and fast-shooting weapon are now available. The locking mechanism is novel to those familiar with machine guns other than the Russian Degtyarev. The present standard dual purpose machine gun of the German Army is the MG 34; the latest known type of German machine gun to have been captured is the MG 42. It seems evident that this weapon is designed to replace the MG 34 although the actual extent of replacement is not known. (For additional details on these weapons see "German Infantry Weapons", Military Intelligence Service, Special Series No. 14 dated May 25, 1943.) Weight with bipod    23 3/4 lbs Length overall 48 in Length of barrel 21 3/4 in Weight of barrel 3 lb 14 1/4 oz Cyclic rate of fire 1,100-1,350 rpm Mounting bipod or tripod Caliber 7.92 mm (.311 in) There is no provision for single shots. a. Comparison with MG 34 By comparison with the MG 34, several interesting new features are noted: (1) Locking System In place of the Solothurn rotating bolt-head of the MG 34, the locking of the bolt to the breech of the barrel is achieved by a wedge, which forces outward, and into suitable recesses in an extension of the breech of the barrel, two rollers on the head of the bolt. As the principle is not familiar to many, at least in its application to ordnance, a simplified diagram illustrative of its action is shown in figures 1 and 2, and a detailed sketch of its application to the MG 42 machine gun is shown in figure 3. (a) Explanation of the Principle It is desired to lock interior tube B (figure 1) securely, but temporarily, to exterior tube A. This locking is accomplished by means of circular (or in some cases spherical) bodies C, which are forced outward through holes E in tube B, into recesses in tube A by means of wedge F, actuated by spring G. When the spherical bodies C are in the position shown in figure 1, inner tube B is free to move within exterior tube A, but when spherical bodies C are thrust outward through the apertures in tube B and engage in the recesses in tube A, the two tubes, A and B are firmly locked together (see figure 2). (b) Application in Model 42 MG This principle is applied in the Model 42 machine gun as follows (see figure 3). On firing barrel A and barrel extension B recoil to the rear until rollers C are cammed inward by fixed cams D unlocking bolt head E and retracting firing pin F. The bolt carrier G and bolt-head continue to the rear guided by fixed guides H while barrel and barrel extension return to battery. On the return of the bolt, the impact of the roller with the camming surfaces I, the "spherical bodies" of figure 1 and 2 on the barrel extension carry the rollers from their seats, and, together with surfaces J on the bolt head, force the rollers outward locking the bolt head to the barrel extension. The initial outward motion of the rollers also frees the firing pin holder K which is driven forward by spring pressure insuring complete locking (by wedging rollers outward) before the firing pin can strike the primer. To extract the bolt-head from the barrel extension, the rollers must be pressed back with the thumb and finger inserted into grooves in the receiver. The bolt-head can then be pulled out. By this system, the gun attains a rate of fire of 1,100 to 1,350 rpm which would appear to be unnecessarily high for a ground gun, though of obvious value for AA fire; the cyclic rate of fire of the MG 34 is from 800 to 900 rpm. Preliminary trials show, however, that this high rate of fire has not been obtained without a certain decrease in accuracy compared with the MG 34. b. Barrel Changing The frequent barrel changing necessitated by the high rate of fire is met by the introduction of a rapid and efficient barrel-changing device. A barrel-change lever is hinged in the right side of the barrel casing, and can be swung outward bringing with it the barrel, which lies in a metal loop attached to the inside of the change lever. The barrel can then be slid out to the rear. c. Unusual Feed Mechanism Feed is by continuous metal belt through a feed block. As in the MG 34, operation is by a feed arm housed in the feed cover. In the MG 42, however, two feed pawls are linked to the front end of the arm by an intermediate link, in such a way that when one is feeding, the other is riding over the next round in the belt. The effect of this is that feed is in two steps instead of one step as in the MG 34, and is therefore much smoother. d. Construction The extensive use of pressing, rivetting and spot-welding in the construction (there are very few machined parts) gives the gun a less-finished appearance than is usual in German weapons. Considerable effort has been made to lighten the gun without the loss of strength - for example by making holes in the operating handle. There is no reason for assuming, however, that its life and performance are not up to the usual German standard.

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