The Five Best US Machine Guns Ever Produced: The United States military has produced some incredible machine guns throughout history, but worldwide, the machine gun has changed warfare forever.

HK421 with ‘para' stock and 330 mm barrel. For illustrative purposes. (Janes/ Amael Kotlarski) Heckler & Koch (H&K) is currently developing a 5.56×45 mm version of the HK421 light machine gun (LMG), ...