SIG MCX Rattler
SIG Sauer Inc. · Personal Defense Weapon · In Production · 2018
Also known as: MCX Rattler, SIG Rattler, CPDW
Overview
The SIG MCX Rattler is an ultra-compact personal defense weapon developed from SIG Sauer's MCX rifle family, built around a short-stroke gas piston operating system and a 5.5-inch barrel. Designed primarily around .300 AAC Blackout to deliver carbine-class terminal performance from a sub-machine-gun-sized envelope, it bridges the gap between SMG and rifle. The platform uses standard AR-15 magazines and parts compatibility, with a side-folding Pivoting Contour Brace (PCB) that collapses the weapon to roughly 432 mm (17 in). In May 2022 USSOCOM awarded SIG a sole-source five-year Commercial PDW contract, citing SIG as the only vendor that could meet the requirement.
Specifications
| Weight (empty) | 2313 g (81.6 oz) |
| Weight (loaded) | 2700 g (95.2 oz) |
| Overall Length | 584 mm (22.99") |
| Folded Length | 432 mm (17.01") |
| Barrel Length | 140 mm (5.51") |
| Height | 203 mm (7.99") |
| Width | 71 mm (2.80") |
| Action Type | Gas Operated Short Stroke Piston |
| Firing Mechanism | Hammer Fired |
| Trigger Type | Single Stage |
| Magazine Capacity | 30 rounds |
| Magazine Type | Detachable Box |
| Muzzle Velocity | 625 m/s (2051 fps) |
| Muzzle Energy | 1585 J (1169 ft·lbf) |
| Effective Range | 200 m (219 yd) |
| Maximum Range | 460 m (503 yd) |
| Rate of Fire | 750 rpm |
| Barrel Rifling | Right Hand |
| Rifling Twist | 127 mm (5.00") |
| Frame Material | Aluminum |
| Barrel Material | Steel |
| Stock Material | Polymer |
| Finish | Black Hardcoat Anodized |
Calibers
- .300 AAC Blackout · primary — also known as 300 BLK, 7.62x35mm
- 5.56x45mm NATO · SS109/M855 — also known as 5.56 NATO
Features
- Firing modes: Semi Automatic, Full Automatic
- Feed systems: Stanag Detachable Box Magazine
- Safety mechanisms: Ambidextrous 90 Degree Manual Safety
- Features: Short Stroke Gas Piston, Rotating Bolt, Two Position Adjustable Gas Regulator, Side Folding Pivoting Contour Brace, Quick Change Barrel, Ambidextrous Controls, Full Length Picatinny Top Rail, M Lok Handguard, Ar15 Magazine Compatible, Suppressor Ready 5 8 24 Threads
Variants
- MCX Rattler PCB — Civilian Pistol Brace
- MCX Rattler SBR — Nfa Sbr
- MCX Rattler Canebrake — Integrally Suppressed
- MCX Rattler LT — Lightweight Updated
- MCX Rattler CPDW (SOCOM) — Select Fire Military
Base model
Service history
Operators
- United States Special Operations Command (USSOCOM) · adopted 2022 · as CPDW
- Australian Army Special Forces · adopted 2024 · as MCX Rattler
- NSW Police Tactical Operations Unit · as MCX Rattler
- Jednostka Wojskowa GROM · as MCX Rattler
- JW Formoza · as MCX Rattler
- Spanish Navy · as MCX Rattler
- Guardia Civil · as MCX Rattler
Production
Production years: 2018-present
USSOCOM Commercial PDW contract awarded May 2022 (sole-source, 5-year). Adopted by SOF and tactical police units in US, Australia, Poland, Spain.
Origin
Country of origin: United States
Notes
Often confused with the larger MCX-SPEAR (basis for the US Army XM7/M7 NGSW rifle) - these are separate platforms in different size and caliber classes. Rifling twist of 1:5 (127 mm) is unusually fast, optimized for stabilizing heavy 220 gr subsonic .300 BLK projectiles. Civilian variants are semi-automatic only; SOCOM CPDW variant is select-fire. Rattler LT (2022+) introduced lighter chassis with longer barrel options (171 mm / 197 mm) and 7.62x39mm chambering option.
Background
Born from a 2017 USSOCOM search for a sub-MP5-sized PDW, the Rattler folds to just 432 mm - small enough to vanish under a low-profile jacket - yet fires intermediate-rifle-class .300 BLK. SOCOM's own justification stated SIG was 'the only vendor that can fulfill USSOCOM's need,' making it the first-ever sole-source SOCOM PDW contract.