The HK 79 is a grenade launcher of German origin. The HK 79 was developed by Heckler & Koch for use on the G3 rifle to provide a similar capability as the US M203. When the HK 79 is attached to a weapon the suffix TGS is added, resulting in the G3 TGS. TGS stands for Tragbares Granat System, which is German for portable grenade system. In English H&K refers to TGS as the Tactical Group System. The HK 79 has been replaced in the H&K product line by the AG36.

The HK 79 is an under barrel grenade launcher for use on the G3 battle rifle. The design has been influenced by the HK 69 stand alone grenade launcher, but is also very different. The frame connects all the parts and acts and attaches to the rifle instead of the original handguard. The steel barrel is hinged at the front and drops down for reloading. The firing pin located at the rear is cocked by hand and a button on the left side of the launcher acts as trigger. The sights are located on the right side of the launcher

The HK 79 is a single shot weapon that fires 40x46mm low velocity grenades. Besides the standard high explosive fragmentation rounds there is a wide variety of other rounds available. Since the barrel drops down rounds of any length can be loaded. The effective range against point targets is 150 m. Area targets can be engaged out to 400 m.

The HK 79 is used by several nations that employ G3 or HK 33 rifles. The most notable users are Greece and Norway. Since the G3 and HK 33 rifles are discontinued by Heckler & Koch the HK 79 is no longer in production.