Ultimax 100: A legendary light machine gun from Singapore

Eric Sof

Ultimax 100 Mk 2 SAW

Having successfully manufactured M16 rifles, M203 grenade launchers, and then their rifle, CIS of Singapore, moved by the U.S. Army SAW (Squad Automatic Weapon) program of the 1970s, decided to make their machine gun and offer it for these. They initially called it the SAW, though in this case, it meant “Section Machine Gun,” but this was soon changed to Ultimax 100, primarily because of the unusual 100-round magazine.

Work began in 1980, but before the design could be perfected, the U.S. Army had selected the FN Minimi as their light machine gun. Nevertheless, the Ultimax 100 proved to be an excellent weapon and was adopted by the Singapore Armed Forces and has been sold to various countries in the Far East, where it has performed well.


The Ultimax 100 is a reasonably conventional gas-operated gun, using a piston to drive a bolt carrier that holds a rotating bolt. It fires from the open bolt position and only fires automatic-single shots are not possible except by careful taps on the trigger, the slow rate of fire helping here.

The first model (Ultimax Mark I) had a quick-change barrel which proved not to be very quick in practice, and it has been dropped. The Ultimax Mark II uses a heavy fixed barrel to fire 500 continuous rounds without heat damage problems. The Ultimax Mark III has a similarly heavy barrel that can be quickly changed when circumstances dictate.


There are various magazines; 20- or 30-round box magazines can be used, or a unique 100-round plastic drum. The weapon can be fired from the shoulder or the hip under complete control with any of these. The sights are fully adjustable for windage and elevation and are graduated up to 1000 meters, a somewhat optimistic marking with 5.56mm ammunition. At shorter ranges to 400-500 meters, though, it is steady, holds well on the target, and is as accurate as its competitors.

Ultimax 100 with drum magazine
Ultimax 100 with drum magazine (Photo: XY)

Technical specifications

Manufacturer:Chartered Industries of Singapore, Singapore
Type:gas-operated, automatic
Caliber: 5.56mm (.223)
Barrel:20 in (508 mm)
Weight (empty):10.8 lbs (4.9 kg) with bipod
Effective firing range:100 to 1200 meters sight adjustments
Rate of fire:520 rounds per minute
Magazine capacity:20,30 or 100 rounds (magazines and drum)

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