Designed to use the standard German fully-powered 7.92×57mm Mauser rifle round and to be cheaper and easier to manufacture, the MG 42 proved to be highly reliable and easy to operate.

[8] It was envisaged and well developed to provide portable light and medium machine gun infantry cover, low level anti-aircraft coverage, and even sniping ability.

Equipped with a quick-change barrel and fed either with non-disintegrating metallic-link belts, or from a 50-round Gurttrommel (belt drum) or a 75-round spring-loaded saddle-drum Patronentrommel 34 magazines (with a simple change of the feed cover for a Trommelhalter magazine holder), the MG 34 could sustain fire for much longer periods of time than other portable squad-level weapons such as the American M1918 Browning Automatic Rifle (BAR), Soviet Degtyaryov machine gun (DP-27) and the British Bren gun, which were fed by magazines, while also being much lighter and more portable than crew-served weapons like the Browning M1919, SG-43 Goryunov or Vickers machine guns (which also lacked quick-change barrels).

The MG 34 was also quite versatile; not only was it able to be fed from belted ammunition or a saddle drum magazine, it could also be fired from a bipod, an innovative Lafette 34 tripod or various pintle mounts for armored vehicles.

However, the MG 34 did have fundamental drawbacks, such as sensitivity to extreme weather conditions, dirt and mud, and comparatively complex and expensive production.

Werner Gruner, one of the leading design engineers with Großfuß, knew nothing about machine guns when he was given the task of being involved with the project, although he specialized in the technology of mass production.

He then recycled an existing Mauser-developed operating system and incorporated features from his experiences with army machine gunners and lessons learned during the early stages of the war.

The initial trials of the Großfuß functional model presented in April 1938 gave rise to improvement requests by the machine gun contest board.

Although made of relatively inexpensive and simple parts, the prototypes proved to be considerably more rugged and resistant to jamming than the precisely machined and somewhat temperamental MG 34.

A limited run of about 1,500 of further improved MG 39/41 pre mass-production model guns, was completed in 1941 and by the end of 1941 tested in combat trials.

[16] Brazilian expeditionary soldiers fighting in Italy used to refer to the MG 42 as Lurdinha; this nickname is due to the fact that the bride of one of the soldiers, named Maria de Lourdes, was a seamstress and the sound of MG 42 was similar to the sound of her sewing machine (Lourdinha is a common nickname in Brazil for women called Maria de Lourdes).

The Americans and the British trained their troops to take cover from the fire of an MG 42, and assault the position during the sub 10 seconds time window of barrel replacement.

[23][24] The Allied nations' infantry doctrines of World War II based a squad's/rifle section's firepower centered on the rifleman and/or a magazine fed light machine gun (BAR, Bren, DP-27/DPM, FM 24/29), and they used weapons with cyclic fire rates of typically 450–600 rounds per minute.

The MG 42's high cyclic rate of fire sometimes proved a liability mainly in that, while the weapon could be used to devastating effect, it could quickly exhaust its ammunition supply.

[6] The machine gun crew member responsible for a hot barrel change was issued protective asbestos mitts to prevent burns to the hands.

The underfolding bipod, the same one used on the MG 34, could be mounted to the front near the muzzle to minimize shot dispersion or the center of the gun near the balance point offering more flexibility depending on how and where it was being used.

Both the cocking handle and the catch for the top cover to the working parts were designed so that the gunner could operate them wearing arctic mittens or with a stick or rod.

In the locked position during firing the rollers rest on parallel surfaces relative to the bore axis on the bolt head ensuring a full lockup.

These two parts start the unlocking sequence after the barrel and bolt assembly have moved 7 mm (0.3 in) rearwards when the parts have moved far back enough that the rollers start the rest on angled/oblique surfaces and allow the rollers to move inwards, controlled by the wedge-shaped front of the striker sleeve, back to their previous position, unlocking the bolt head and allowing the bolt assembly to further recoil rearwards, extracting the spent cartridge case and ejecting it downwards 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.

[35] A more practical solution to control the harmonics problem in the roller/wedge system and make the MG 42 less ammunition ignition timing sensitive was needed.

The roller-locking system inherent problem was solved after World War II by developing and adding bolt-bounce preventing bolt catches to the action.

According to Infantry Journal in 1947, the operating momentum driven MG 42 feed system will not function reliably under a cyclic firing rate of 850 rounds per minute.

The Lafette 42 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.

- Spitzgeschoß mit Eisenkern (spitzer with iron core) ammunition of which the external ballistic behaviour started to significantly deviate from 1,500 m (1,640 yd) upwards compared to the s.S. Patrone (s.S. ball cartridge).

The MG 45 had some influence in the post-war development of roller-delayed blowback system, as employed in issued CETME, SIG and Heckler & Koch small arms.

[58][59] Saginaw Steering Gear Division of General Motors received a contract to construct two working converted MG 42 prototypes designated as the T24 machine gun.

[59] However, the realization that the .30-06 Springfield cartridge was too long for the prototype gun's mechanism to easily and reliably work with resulted in the discarding of the project.

[59] Saginaw Steering Gear did not get the opportunity to correct the flaws that caused the inability to obtain reliable uninterrupted automatic functioning and further optimize and ready the weapon for mass production before World War II ended.

The resulting weapon had a cyclic rate of fire of 1,000 rounds per minute, was in the light machine gun role 4.4 kg (9.70 lb) heavier than the German MG 42, and much more finely made and finished.

But to introduce a modern weapon of its own production the Office of Defence Technology, in cooperation with Steyr Mannlicher and Beretta developed a gun specifically for the Austrian Army.