All modern, first-rate armies of the world field some form of Automatic Grenade Launcher (AGL). These are belt-fed weapons suitable for fire suppression efforts and can be fitted to defensive positions (firing from a heavy-duty tripod assembly) or mounted on vehicles and watercraft (via pintle mount). For the Republic of Korea Army (South Korea), the Daewoo Precision Industries "K4" fulfills this battlefield role. It entered service in 1993 and has seen combat in the wars in Afghanistan and Iraq and has also seen exposure in the Libyan Civil War.
Design work on the K4 spanned from 1985 to 1991 and was handled by the Agency for Defense Development. The weapon is a product of a decisive move by South Korean armed forces to reduce reliance on foreign military products. As such a whole line "K" weapons have since emerged and stocks the inventory of the modern South Korean Army. Many of the K-weapons are today (2017) produced under the S&T Motiv brand label.
In many ways, the South Korean K4 mimics the form and function of the well-established American-originated Saco Mk 19 AGL still in widespread use around the globe. Like the Mk 19, the K4 relies on the proven 40x53mm grenade which offers good concussion and explosive effects against target areas. The internal firing action is of basic blowback and feeding is by way a belt pulled from a hard case - projectiles enter the receiver from the left side and spent cases are ejected to the right. A rate-of-fire nearing 350 rounds-per-minute can be achieved and effective engagement ranges are out to 1,500 meters while areas out to 2,200 meters can be affected though with reduced accuracy. Sighting is through a flip-up rear aperture.
The single-shot, under-barrel launcher form of the K4 is the "K201" detailed elsewhere on this site. This more compact weapon provides a grenadier capability to the standard infantryman and broadens his tactical value in the field.
Beyond South Korea, the K4 has been purchased by Libya (becoming the product's first export customer in 2009) and Mexico (becoming an operator in 2011).