A G36 light machine gun that runs on drums. The UK Arms 2500 round drum is made for MK36/G36 series guns, like the one in the photo. The Classic Army 470 round mag is the maker's own G36 magazine for a lighter setup. Example build by LoadoutLab. Every part is listed by its shop as made for this gun. Photo: "Airsoft MG36.JPG" by BrokenSphere, CC BY-SA 3.0, via Wikimedia Commons (https://commons.wikimedia.org/wiki/File:Airsoft_MG36.JPG). The photo shows this gun model; the parts list is a suggested setup.