Putting 700 rounds through a M249 SAW machine gun.
Machine gun synchronizer - video
.50 caliber machine gun cutaway - GIF
Miniature Browning machine gun - GIF
Soviet machine gun belt loading tool - GIF
Belarusian machine gunner with 580-round ammo backpack - photo
Machine gun synchronizer in slow motion - GIF
Miniature Thompson submachine gun with violin case - video