ST Kinetics Ultimax 100
ST Kinetics (ST Engineering Land Systems) · Machine Gun · In Production · 1982
Also known as: Ultimax, CIS Ultimax 100
Overview
The Ultimax 100 is a Singaporean 5.56x45mm NATO light machine gun developed by Chartered Industries of Singapore (now ST Kinetics) in the late 1970s. Its standout feature is an unusually low felt recoil thanks to a constant-recoil operating system pioneered by designer L. James Sullivan, in which the bolt carrier never bottoms out against the rear of the receiver. The Ultimax 100 is renowned for being one of the most controllable LMGs in service, allowing accurate one-handed automatic fire.
Specifications
| Weight (empty) | 4750 g (167.6 oz) |
| Weight (loaded) | 6800 g (239.9 oz) |
| Overall Length | 1030 mm (40.55") |
| Barrel Length | 508 mm (20.00") |
| Action Type | Gas Operated Long Stroke |
| Firing Mechanism | Hammer Fired |
| Trigger Type | Single Stage |
| Magazine Capacity | 100 rounds |
| Magazine Type | Drum |
| Muzzle Velocity | 970 m/s (3182 fps) |
| Muzzle Energy | 1880 J (1387 ft·lbf) |
| Effective Range | 1000 m (1094 yd) |
| Maximum Range | 2000 m (2187 yd) |
| Rate of Fire | 500 rpm |
| Barrel Rifling | Right Hand |
| Rifling Twist | 178 mm (7.01") |
| Number of Grooves | 6 |
| Frame Material | Steel |
| Barrel Material | Steel |
| Stock Material | Polymer |
| Finish | Phosphate |
Calibers
- 5.56x45mm NATO · primary · SS109 — also known as 5.56 NATO, .223 Remington (parent)
Features
- Firing modes: Full Automatic
- Feed systems: 100 Round Drum Magazine, Stanag Box Magazine
- Safety mechanisms: Manual Safety, Open Bolt
- Features: Constant Recoil Operating System, Quick Change Barrel, Folding Bipod, Carrying Handle, Picatinny Rail, Stanag Magazine Compatibility
Variants
- Ultimax 100 Mk1 — Early Quick Change Barrel
- Ultimax 100 Mk2 — Fixed Barrel
- Ultimax 100 Mk3 — Qcb Standard Compact
- Ultimax 100 Mk4 — Iar Competitor
- Ultimax 100 Mk5 — Modernized Picatinny
- Ultimax 100 Mk8 — Improved Export
- Ultimax 100 Mk9 — Current Modular
Service history
Operators
- Singapore Armed Forces · adopted 1982 · as Ultimax 100
- Royal Brunei Armed Forces
- Croatian Armed Forces
- Indonesian National Armed Forces
- Peruvian Armed Forces
- Armed Forces of the Philippines
- Slovenian Armed Forces
- Zimbabwe Defence Forces
Conflicts
- East Timor Conflict (1975-1999)
- Moro conflict (1969-2019)
- UN Peacekeeping operations (1989-present)
Production
Estimated total produced: 80,000 · Production years: 1982-present
Approximately 80,000 units produced; primarily for Singapore Armed Forces with export to multiple Asian and South American operators
Origin
Country of origin: Singapore
Designer: L. James Sullivan
Notes
The constant-recoil principle was inherited from Sullivan's earlier work on the Stoner 63. The Mk9 variant, unveiled at Singapore Airshow 2024, modernizes the platform with a side-folding stock, M-LOK handguard, and improved feeding from STANAG magazines.
Background
The Ultimax 100 is so smooth in operation that ST Kinetics famously demonstrated it being fired one-handed and even with the operator holding the barrel, the recoil being closer to a 5.56mm carbine than a typical squad automatic weapon.