The G8A1 is the Bundeswehr and Bundespolizei designation of the Heckler & Koch HK11, a 7.62mm magazine-fed general purpose machine gun from Germany. appears in Rainbow Six Siege.
Despite the in-game designation, this weapon is a hybrid of the 5.56mm belt-fed Heckler & Koch HK23 and the 5.56mm mag-fed Heckler & Koch HK13: The magazine well is a key feature of the HK13, but the receiver design, with its longer ejection port and a large, tubular brass deflector, is almost never found on the mag-fed HK machine guns, and instead comes from the belt-fed HK machine guns like the HK23. It has a G3 rear sight and added rails.
The G8A1 has a fast firing rate and utilises a 50-round drum magazine, allowing it to reload faster than those that use belt-feed systems. Combined with its fast firing rate of 850, this allows the G8A1 to shine with the assault rifles, to an extent, whilst giving much greater firepower.
When compared to the V308, the use of significantly smaller drum magazines would suggest the G8A1 is being used in a 5.56 NATO magazine-fed configuration, a possibility since the HK21's design allows for modular caliber conversions.