With a long-running history in design, development and production of excellent grenade launchers, Milkor Pty Ltd of South Africa took their expertise to the under-barrel launcher market resulting in the 40mm Mk-4 UBGL ("Under-Barrel Grenade Launcher"). Due to the entrenched nature of certain automatic rifles such as the American Colt M16, Heckler & Koch G3 and Soviet/Russian AK-47 types, the UBGL was specifically designed to adapt to these in-play systems. The Mk-4 can, therefore, connect to such assault weapons by way of a Picatinny or STANAG-style accessories rail or even more custom-made attaching solutions. The UBGL was introduced into the Milkor company line up in 2006.
The ability for a modern warfighter to integrate a grenade-launching solution is second to none, turning the standard infantryman into his own fire support grenadier. The under-barrel nature of such launching systems keeps the host weapon's dimensions in check, the attacked launcher utilizing the existing magazine as a grip handle. The Mk-4 features a cylindrical appearance tapering towards the muzzle. The mounting gear is along the top and fits under the host weapon's handguard in the typical way. Loading/reloading requires the frontal section of the launcher to be swung out to expose the breech. The UBGL is regarded as a lightweight design, adding little to the weight of an existing, fully-loaded weapon. The barrel is made of steel for robustness and wear and is internally rifled for accuracy. The system makes use of the widely-accepted low-velocity 40mm grenade. These grenades are further offered in various payload/warhead types spanning lethal, non-lethal and tactical breeds. The entire Mk-4 device can be quickly removed if need be by management of a simple release clip. The weapon can also be fired as a standalone system if required.
Due to the engagement nature of grenade launchers, the Mk-4 if given a minimum listed range as well as a maximum range for operator safety. The minimum range is listed at 30 meters with an effective range out to 250 meters though 350 meters is possible under certain circumstances. A trained/experienced operator can sustain a rate-of-fire of six rounds per minute. Sighting is though a saddle sighting device though a ladder and aim point system can also be utilized.