One interesting thing about weapons is that most development is evolutionary, rather than revolutionary. What I mean by that is that when a weapon is introduced it almost immediately begins to be modified and tweaked to meet current needs and overcome deficiencies. Over time, becomes a very different weapon. This is the main way the technology advances, rather than a new weapon with amazing, never before seen capabilities.
Here we have the final evolution of one of the greatest guns of its era, the Browning M1919 machine gun. The M1919A6 was developed for Airborne troops and it was used a "light" machine gun by the Marines in the Pacific theater of WWII. It has been extensively modified from the original to allow the gunner to operate what was a crew served weapon by himself. (At least mostly.) The M1919 was itself an air cooled descendant of the water cooled machine guns of the WWI era. A lighter barrel was mounted to take off some the extremely heavy weight of the original M1919. It has a light bipod versus the very heavy tripod that was usually used. To keep the belts of .30-06 rounds out of the dirt, it has been given a simple aluminum box to feed its ammo. It was finished off with a muzzle brake/flash hider and a buttstock to increase its accuracy. The end result was a more useful weapon although, the appellation of "light" machine gun was perhaps not the best one, as it clocked in at over 33 pounds, with no ammunition. In comparison, the current light machine gun, the Mk 48, Mod 0 is only about 17 pounds. The M1919 series is as tough as a coffin nail, and weapons of its type are still in service around the world. Wartime necessity and ingenuity improved it and brought it as far as it could go as an infantry weapon, as we see here.