The M79 grenade launcher is a weapon in Fallout Tactics.
One of the earliest United States grenade launcher designs, built around the 40mm grenade. Utilizing the High-Low propulsion system, the M79 allows the operator to deliver high explosive rounds at a range of hundreds of meters, while its rugged design - consisting of just five major parts, a receiver, fore-end, barrel, sight, and stock - offers excellent reliability. The one drawback is that the grenade launcher is single-shot only, reducing its rate of fire and precluding a sustained volume of fire. However, it is quite compact, especially with the stock sawed off, while the straightforward optics, consisting of a fixed blade sight on the front and a folding leaf sight on the rear, enable accurate fire with just pointing and shooting. These qualities kept it in use well into the late 21st century, showing that simplicity is beauty.
A moderately powerful, fairly accurate single-shot weapon, the grenade launcher functions as a sort of mid-way between a conventional rifle and a submachine gun. It has significantly more power behind it per-shot than any of the real submachine guns, but it doesn't have quite as much stopping power and reliability as a sniper rifle, due mostly in part to the single grenade. They end up being very useful for a recruit that had previously specialized in close-range weapons, but the splash damage does deter their use for that as well.
The grenade launcher uses the same animations and models as any of the submachine guns; it can be hard to tell whether a Reaver is using a grenade launcher or an AUG.