ST Kinetics Ultimax 100 Mk5
ST Kinetics (ST Engineering Land Systems) · Machine Gun · In Production · 2000
Also known as: Ultimax 100 Mark 5, U100 Mk5
Overview
The Ultimax 100 Mk5 is the modernized production version of ST Kinetics' 5.56x45mm light machine gun, originally designed by American engineer James Sullivan for Chartered Industries of Singapore in the late 1970s. The Mk5 adds a folding buttstock, a Picatinny rail accessory system, support for both STANAG box magazines and the 100-round drum, and a quick-change barrel over the earlier Mk3/Mk4. Its defining feature is the constant-recoil operating system, which keeps the bolt from ever bottoming out against the receiver, giving the Ultimax exceptionally low felt recoil and outstanding full-auto controllability, among the most controllable LMGs ever fielded.
Specifications
| Weight (empty) | 4750 g (167.6 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 | 1881 J (1387 ft·lbf) |
| Effective Range | 460 m (503 yd) |
| Maximum Range | 1000 m (1094 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: Detachable Box Magazine, Drum Magazine
- Safety mechanisms: Manual Safety
- Features: Constant Recoil System, Folding Buttstock, Quick Change Barrel, Picatinny Rail, Stanag Magazine Compatible, Rotating Bolt, Bipod, Air Cooled
Variants
- ST Kinetics Ultimax 100 Mk3 — Earlier Model
Base model
Service history
Operators
- Singapore Armed Forces
- Croatian Armed Forces
- Philippine Armed Forces
Production
Estimated total produced: 80,000 · Production years: 2000-present
Approximate cumulative production across the Ultimax 100 family; Mk5-specific figures not published
Origin
Country of origin: Singapore
Designer: James Sullivan
Notes
The constant-recoil design allows accurate offhand and even one-handed automatic fire, a hallmark widely praised in evaluations. The Mk5 is distinct from the later Mk8 and lightweight Mk9 iterations.
Background
The Ultimax 100's constant-recoil system is so smooth that demonstrators routinely fire it accurately one-handed. Its designer James Sullivan also co-developed the Stoner 63 and helped refine the original AR-15.