Colt M16 LMG, M16 LMG and Ultimax 100 Mk4 Assault Rifle

At the National Defense Industries Association small arms symposium in May 2006 Colt Defense unveiled the prototype of its new Colt M16 LMG which is clearly aimed at the IAR project. Unlike earlier proposed M16 support variants, the M16 LMG assault rifle features a quick change barrel. Fed from standard 20- and 30-round NATO magazines or the Beta 100-round C-Mag the weapon has a rate of fire of 700 rpm. A Mil-Std- 1913 rail is integrated on the flat top upper receiver to accommodate day or night sights with flip up iron sights mounted as a back up.

The M16 LMG can be supplied with either an M4 carbine style extending butt stock or a fixed M16 stock. Selection of the M16 LMG for employment alongside the service’s new M16A4 assault rifles would have obvious advantages in terms of training and support. The M16 LMG faces a serious rival for the IAR requirement in the form of the new Mk 4 version of Singapore Technologies Kinetics Ultimax 100. The company notes that at 4.9 kg the original Ultimax 100 “still holds the record for being the lightest 5.56mm calibre machine gun in the world”.

The weapon was designed to be used with a unique 100-round drum magazine although it accepts modified NATO magazines. A forward pistol grip is fitted for easy handling and low recoil forces enable the Ultimax 100 to be fired with the buttstock removed. Unlike other machine guns that rely upon the weight of the receiver to absorb recoil force all versions of the Ultimax are based on the ‘Constant Recoil’ principle which reduces recoil and muzzle rise thus allowing for better control when the weapon is fired in automatic mode.

Firing NATO standard SS109 ammunition the Ultimax 100 has an effective range of 1,300 m although customers can specify a barrel rifled for the US M193 round with a drop in maximum range to 460 m. The original Ultimax 100 had a fixed barrel but the current Mk 3 version is available with quick change 508 mm standard and 330 mm short barrels.

The Ultimax 100 Mk4 was evaluated by the USMC alongside the Minimi and other LMGs in the 1980s and rated very highly although the corps endorsed the US Army’s choice of the Minimi. Modifications in the new Ultimax 100 Mk 4 include replacing the original two position (‘safe’ and ‘automatic’) change lever to allow semi-automatic and automatic fire, mounting a Mil-Std-1913 rail on the top receiver and also at the 3, 6 and 9 o’clock positions on the forward handguard. The weapon accepts standard NATO magazines as well as the Beta C-Mag; L James Sullivan who designed the Ultimax 100 also designed the C-Mag.