SIG Sauer MCX Virtus SBR
SIG Sauer · Carbine · In Production · 2018
Also known as: MCX Virtus SBR, SIG MCX .300 BLK, MCX Virtus 300 Blackout
Overview
The SIG Sauer MCX Virtus SBR is a compact short-barreled rifle chambered in .300 AAC Blackout, designed as a suppressed close-quarters weapon system for special operations and law enforcement use. Featuring a 9-inch cold hammer-forged carbon steel barrel with a 1:5 twist rate optimized for both subsonic and supersonic .300 BLK loads, the Virtus SBR provides maximum effectiveness in a package that measures just 19.5 inches with the stock folded. The MCX platform's signature short-stroke gas piston operating system eliminates the buffer tube requirement found in traditional AR-15 platforms, enabling the side-folding and 5-position collapsing stock that gives the rifle its remarkably compact profile. The Matchlite Duo trigger provides a crisp, clean break for improved accuracy, while free-floating M-LOK handguards accommodate accessories without affecting barrel harmonics. The internal recoil system reduces felt recoil, particularly beneficial when firing suppressed. The .300 Blackout chambering is specifically chosen for its exceptional performance with suppressors, delivering subsonic loads that are hearing-safe while maintaining terminal effectiveness at close quarters.
Specifications
| Weight (empty) | 3175 g (112.0 oz) |
| Weight (loaded) | 3630 g (128.0 oz) |
| Overall Length | 724 mm (28.50") |
| Folded Length | 495 mm (19.49") |
| Barrel Length | 229 mm (9.02") |
| Action Type | Gas Operated Short Stroke Piston |
| Firing Mechanism | Rotating Bolt |
| Trigger Type | Single Stage |
| Magazine Capacity | 30 rounds |
| Magazine Type | Detachable Box |
| Muzzle Velocity | 716 m/s (2349 fps) |
| Muzzle Energy | 2041 J (1505 ft·lbf) |
| Effective Range | 300 m (328 yd) |
| Maximum Range | 460 m (503 yd) |
| Barrel Rifling | Right Hand |
| Rifling Twist | 127 mm (5.00") |
| Number of Grooves | 6 |
| Frame Material | Aluminum Alloy |
| Barrel Material | Cold Hammer Forged Carbon Steel |
| Stock Material | Polymer |
| Finish | Matte Black |
Calibers
- .300 AAC Blackout · primary — also known as 300 BLK, .300 Blackout, 7.62x35mm, 300 AAC BLK
Features
- Firing modes: Semi Automatic
- Feed systems: Detachable Box Magazine, Stanag Compatible
- Safety mechanisms: Ambidextrous Safety, Firing Pin Safety
- Features: Folding Stock, Collapsible Stock, Short Stroke Piston, User Changeable Barrel, Suppressor Optimized, M-Lok Handguard, Matchlite Duo Trigger, Internal Recoil System, Ambidextrous Controls, Ar15 Magazine Compatible
Base model
Service history
Operators
- US Special Operations Forces (Various)
- US Law Enforcement (Various)
Production
Production years: 2018-present
In active production. The MCX platform is one of SIG Sauer's flagship military and law enforcement products.
Origin
Country of origin: United States
Notes
The MCX Virtus SBR in .300 BLK represents the convergence of two design philosophies: the MCX's piston-driven, folding-stock architecture and the .300 Blackout cartridge's suppressor optimization. The 1:5 twist barrel is deliberately fast to stabilize the heavy 220-grain subsonic projectiles commonly used in suppressed operations, while still performing well with lighter supersonic loads. The user-changeable barrel system allows caliber conversion between .300 BLK and 5.56 NATO with basic tools. The MCX platform has been adopted by various US special operations units and law enforcement agencies, though specific unit designations are not publicly disclosed. The Virtus generation of the MCX introduced the Matchlite Duo trigger and updated handguard system.
Background
The MCX Virtus SBR in .300 Blackout is the quiet professional's tool of choice. With the stock folded, it fits inside a standard backpack; with a suppressor threaded on and subsonic ammunition loaded, it delivers lethal force with less noise than a car door slamming. The combination of the MCX's folding stock and the .300 BLK's suppressor-friendly ballistics created a weapon system that redefined what 'concealable firepower' means for tier-one operators.