Operating system The MG 34 fires from an
open bolt and this format both keeps the barrel open at both ends after firing ceases, allowing airflow through it and helping it to cool faster, and meanwhile retains the next unfired bullet outside the chamber until the trigger is squeezed again; and thus the cartridges are protected from the risk of
cook-offs from high chamber temperatures after long bouts of sustained automatic fire. The firearm was designed with a
rotating bolt operated by
short recoil aided by a
muzzle booster. When the firearm is ready to fire the bolt is pulled back to the rear and is held back by the
sear. With the pull of the trigger the sear disengages sending the bolt forward under pressure from the recoil spring. A cartridge is stripped from the magazine or belt and the round is pushed into the chamber. As the bolt moves forward into battery the bolt rotates engaging the locking lugs and chamber locking the bolt to the barrel. The
striker strikes and ignites the primer and the round is fired. The recoil causes the barrel and bolt to move backwards a short distance. The rearward movement of the barrel causes the rotating bolt to rotate back disengaging the locking lugs and unlocking the bolt from the barrel. The barrel returns to its forward position while the bolt recoils to its rear position. The spent cartridge case is ejected downward through an ejection port normally covered by a spring-loaded dust cover at the bottom of the receiver, just in front of the trigger group and the cycle can begin anew. The spring-loaded dust cover automatically opens when the gun is fired, but the user has to close it after firing to prevent dirt entering the receiver through the open port.
Sights The MG 34 came with a standard
iron sight line consisting of a notched 'V' sight mounted to a post in the rear and a single blade at the front. The sight came calibrated for ranges between in meter increments. The standard sight line had a sight radius. The MG 34 could accept a variety of different sighting systems, such as a spider web-type anti-aircraft sight or telescopic sights for use in specialty roles. An
active infrared device, intended primarily for night use, and consisting of a specialized mount, active infrared spotlight and accompanying infrared image converter was developed that could be used with the MG 34 and MG 42. In the later stages of World War II the bulky
Fahr- und Zielgerät FG 1250 (driving and aiming device
FG 1250) active infrared unit was paired on
Sd.Kfz. 251/1 Falke half-track armored personnel carriers to some MG 34 and MG 42 machine guns.
Feeding The MG 34 could use
non-disintegrating metallic-link belts, which have links that wrap around the cartridge case and are linked by a coiling wire on each side. The belts are intended for multiple reuse. Operation through the feed block is in one step by a feed arm housed in the feed cover. According to U.S. Ordnance Department tests, performed in 1942, the MG 34 was capable of lifting 75 rounds of belted ammunition during firing. The feeding system was based on the direct push-through of the cartridge out of the link into the gun's chamber. Accordingly, the link had to be of the half-open type to enable the motion of the bolt through the link. During World War II the
Gurt 34/41-belt family was introduced.
Gurt 34/41 belt links and wire spirals were made of thinner material — the
Gurt 34 links were made of and
Gurt 34/41 links of thick stamped steel sheet metal — that saved ⅓ of metal and counterintuitively yielded improved performance. Belts were supplied in a fixed length of 50 rounds, but could be linked up to make longer belts for sustained firing. Ammunition boxes contained 250 rounds in five 50-round belts. A 250-round
Patronengurt 33 belt was also issued to machine guns installed in fixed emplacements such as bunkers.
Patronenkasten 34 and
Patronenkasten 41 ammunition boxes could hold up to 300 belted rounds. The
Patronenkasten could contain an
Einführstück belt starter-segment. The 50-round
Gurttrommel assault drum designed to be clipped to the left side of the gun was an alternative feed option. It was not a true magazine but held a coiled 50-round belt and corresponding
Einführstück starter-segment preventing it from snagging, twisting and getting stuck during mobile assaults. The
Gurttrommel belt container was commonly used until the end of World War II, with the MG 34 and MG 42. The 75-round
Patronentrommel 34 "double drum" magazine was the original pre-redesign feed method. This double drum or saddle magazine type was introduced on the
MG 13, but the MG 13 magazine and
Patronentrommel 34 were not interchangeable. After the MG 34 redesign, that enabled the MG 34 to use belted ammunition, the
Patronentrommel 34 became a rare alternative feed option. The
Patronentrommel 34 could be used only together with a
Trommelhalter magazine holder that substituted the normal feed cover, thereby switching the gun from belt feeding to
Patronentrommel 34 "double drum" magazine feeding. It contained 75 loose rounds in two spring-powered spirals twisting in opposite direction, feeding the chamber from opposite sides in turn. The
Patronentrommel 34 was rather complicated and inconvenient to (re)load, adjust to work reliably, and in use.
Trigger A notable feature of the MG 34 was its double-crescent trigger, which provided
select fire capability without the need for a fire mode selector switch. Pressing the upper segment of the trigger produced
semi-automatic fire, while holding the lower segment of the trigger produced
fully automatic fire. Though considered innovative at the time, the feature was eliminated due to its complexity on the MG 34's successor, the MG 42. The lower section has a restrictor built in the trigger allowing it to be pulled further back if pressed by the user. The safety switch has a secure double safety requiring the user to push in the notch and sliding over until it locks in place in safe/fire modes. Trigger groups on examples used on the eastern front used aluminium grip panels as bakelite tended to crack in the cold. In the light machine gun role, it was used with a bipod and weighed only . In the
medium machine gun role, it could be mounted on one of two tripods, a smaller one weighing , the larger
Lafette 34 .
Lafette 34 tripod For the medium machine gun role a larger tripod, the MG 34
Lafette 34, included a number of features, such as recoil absorbing buffer springs, a
Zielfernrohrhalter (optical sight mounting bracket) for mounting an MG Z 34 or MG Z 40 periscope-type 4× power
telescopic sight containing special sighting equipment for
indirect fire or the late World War II MG Z 44, designed for direct fire only. Fitting such an optical sight enabled the machine gun to deliver direct fire out to . An accessory to lengthen these sights' periscope was available, allowing the use of them behind cover. The
Lafette could be set up in a prone, kneeling or a high position and weighed on its own. The legs could be extended with a
Lafetteaufsatzstück to allow it to be used in the low level anti-aircraft role, and when lowered, it could be placed to allow the gun to be fired "remotely" while it swept an arc in front of the mounting with fire. Mounted to the
Lafette and aimed through the MG Z 34 or MG Z 40 telescopic sight the effective range of the MG 34 could be extended out to when fired indirectly. The indirect firing method exploits the
s.S. Patrone useful maximum range, that is defined by the maximum range of a small-arms projectile while still maintaining the minimum kinetic energy required to put unprotected personnel out of action, which is generally believed to be 15 kilogram-meters (147 J / 108 ft⋅lbf). The
Lafette 34 tripod also had a bolt box to store a (spare) bolt. Another unique feature of German World War II machine guns was the
Tiefenfeuerautomat feature on the
Lafette 34 tripod. If selected, this feature mechanically controlled the rise and fall of the gun, elevating the gun for five rounds and then depressing it for four rounds. It lengthened the
beaten zone by walking the fire in wave like motions up and down the range in a predefined area. The length of the beaten zone could be set on the
Tiefenfeuerautomat. E.g., being unsure whether the real distance was , the gunner could make the mount do an automatic sweep between the elevations for and back. This sweeping of a selected beaten zone continued as long as the gun fired. The
Lafette 34 had a
Richt- und Überschießtafel (Overhead firing table) riveted to the rear body of the searchfire mechanism from the very start of production until the very end of it. In the later stages of World War II ballistic correction directions were added for overshooting friendly forces with
S.m.E. – Spitzgeschoß mit Eisenkern (spitzer with iron core) ammunition of which the external ballistic behaviour started to significantly deviate from upwards compared to the
s.S. Patrone (s.S. ball cartridge). A trigger handle, which enabled the operator to fire the gun without affecting the stability of the gun's point of aim, was attached to the
Tiefenfeuerautomat searchfire unit. On the
Lafette 34 it could be adjusted for both semi-automatic firing and full-automatic firing mode, although some simplified late-war mounts had the trigger configured for full-automatic firing mode only. There were numerous other specialist mounts for the MG 34. The
Dreibein 34, for example, was a simple high-standing tripod for mounting the gun in anti-aircraft mode. There were also mounts for bicycles, motorcycle sidecars, tanks and armoured vehicles (ball and pintle mounts), fortress positions, boat decks and even assault gliders. MG 34s were mounted in multiple-gun arrangements, particularly on vehicles, for low level anti-aircraft defence. The stock could be easily removed to reduce the space occupied when mounted inside a vehicle. It was produced in various wood and bakelite versions. ==Variants==