During the attack on Muttaqi at hideout, around 0:35:56 - 0:36:06 "Buck" is advancing while shooting and then getting wounded. Right after Robert arrives and report man down
Buck says "take the SAW" and at 0:36:54 - 0:36:57, Robert is seen lay down suppressive fire.
This SAW is a FN MK 46 LWMG, and even though belt-fed, the belt visible doesn't move during close ups.