Belt Fed semi-automatic machine guns.

You can own a belt fed semi-automatic machine gun like the M249S SAW, M240B, the Browning M2 .50 Caliber and the RPD.

A belt or ammunition belt is a device used to retain and feed cartridges into a firearm. Belts and the associated feed systems are typically employed to feed machine guns or other automatic weapons. Belt-fed systems minimize the proportional weight of the ammunition to the feeding device along with allowing high rates of continuous fire. The capacity of belts and carriers is typically a function of weight and bulk. Their size is limited by caliber and the portability of the combined weapon and ammunition. The most common sizes typically carried on a man-portable weapon run from 50 to 300 rounds.

Belt Fed – Wikipedia