An interim LMG that was used very, very briefly in the German army prior to WW2, the MG-13 is chambered in 7.92mm, with the name MG-13 which most people thought was made in the year 1913 but that was just a little trick to fool ze watchdogs.
Features a side loading magazine well, the machinegunner can deploy the stock fully and its bipod, supported by the large swinging carrying handle. Pop open the dust cover, load your magazins in, charge the weapon and let it fly. Features a dual-trigger-ish crescent system, we just assume progressive trigger for the sake of H3.
Other interesting feature is its unique bolt release button, the flippable sights and adjustable spring tension that make your rate of fire faster or slower.
Model from Enlisted; Thanks Catt, with more thanks to Marcus for the support!