Sig Sauer126823360
SIG MCX Rattler LT 5.56 SBR, 7.75" Barrel, Black, 30-Round Capacity$2,499.99
Availability: In Stock
Current Stock: Out of stock
The SIG MCX Rattler LT 300 Blackout SBR is a purpose-built short-barrel rifle that combines SIG's proven MCX platform with the ballistic efficiency of 300 Blackout—ideal for close-quarters shooting, suppressed setups, and tactical applications where compact size and modularity matter. This is the lighter, more adaptable evolution of the original Rattler, featuring a cold hammer-forged 6.75" barrel that keeps overall length to just 17.25 inches while delivering the subsonic and supersonic performance 300 Blackout shooters rely on.
Built around a short-stroke piston operating system, the MCX Rattler LT runs clean and reliably in suppressed and unsuppressed configurations. The adjustable gas piston lets you dial in the right amount of back-pressure for your ammunition and suppressor setup, eliminating the guesswork. Every control is fully ambidextrous—bolt catch, bolt release, and safety—so lefties and righties operate the gun the same way. The flat-blade match trigger is crisp and predictable, and the SIG suppressor-ready flash hider (SLX/SLH compatible) threads on without modification.
What sets the LT apart is its modularity. The barrel is now fully compatible with all MCX handguards and barrels in the LT lineup, so you can swap calibers, barrel lengths, and rail systems to adapt the rifle to your mission. M1913 accessory rails give you plenty of real estate for optics, lights, and other gear. At 5.8 pounds, it's nimble enough for CQB and tactical work while remaining solid enough for precision shooting at distance. One 30-round AR-15-pattern magazine comes in the box.
If you're running suppressed 300 Blackout or building a versatile short rifle that doesn't compromise on ergonomics or reliability, the MCX Rattler LT earns its place on the roster.
| Caliber | 300 Blackout |
| Barrel Length | 6.75 inches |
| Barrel Material | Cold Hammer Forged Carbon Steel |
| Twist Rate | 1:5 |
| Overall Length | 17.25 inches (171.5 mm) |
| Collapsed Length | 17 inches |
| Overall Width | 2.25 inches (57.2 mm) |
| Height | 7.4 inches (187.2 mm) |
| Weight | 5.8 lbs (2.6 kg) |
| Action | Semi-Automatic |
| Operating System | Short-Stroke Piston |
| Trigger Type | 2-Stage Match / Flat-Blade |
| Grip | PDW |
| Magazine Type | AR-15 Pattern |
| Magazine Capacity | 30 rounds |
| Magazines Included | 1 × 30-round Polymer Magazine |
| Accessory Rail | M1913 Picatinny |
| Flash Hider | SIG QD Suppressor-Ready (SLX/SLH Compatible) |
Yes. The rifle ships with a SIG suppressor-ready flash hider (SLX/SLH compatible) already installed and pinned. The adjustable gas piston also allows you to tune the rifle for optimal performance with a suppressor attached, whether you're running subsonic or supersonic ammunition.
Yes. The MCX Rattler LT is fully modular. The barrel is compatible with all MCX LT barrels and handguards, so you can change calibers, barrel lengths, and rail systems to suit your needs.
The rifle uses standard AR-15 pattern magazines. One 30-round polymer magazine is included in the box.
Yes. All controls—bolt catch, bolt release, and safety—are fully ambidextrous, making the rifle equally comfortable for left- and right-handed shooters.
SKU: 126817118 • Weight: 7.8oz
Availability: In Stock
Current Stock: Out of stock
The SIG MCX Rattler LT 300 Blackout SBR is a purpose-built short-barrel rifle that combines SIG's proven MCX platform with the ballistic efficiency of 300 Blackout—ideal for close-quarters shooting, suppressed setups, and tactical applications where compact size and modularity matter. This is the lighter, more adaptable evolution of the original Rattler, featuring a cold hammer-forged 6.75" barrel that keeps overall length to just 17.25 inches while delivering the subsonic and supersonic performance 300 Blackout shooters rely on.
Built around a short-stroke piston operating system, the MCX Rattler LT runs clean and reliably in suppressed and unsuppressed configurations. The adjustable gas piston lets you dial in the right amount of back-pressure for your ammunition and suppressor setup, eliminating the guesswork. Every control is fully ambidextrous—bolt catch, bolt release, and safety—so lefties and righties operate the gun the same way. The flat-blade match trigger is crisp and predictable, and the SIG suppressor-ready flash hider (SLX/SLH compatible) threads on without modification.
What sets the LT apart is its modularity. The barrel is now fully compatible with all MCX handguards and barrels in the LT lineup, so you can swap calibers, barrel lengths, and rail systems to adapt the rifle to your mission. M1913 accessory rails give you plenty of real estate for optics, lights, and other gear. At 5.8 pounds, it's nimble enough for CQB and tactical work while remaining solid enough for precision shooting at distance. One 30-round AR-15-pattern magazine comes in the box.
If you're running suppressed 300 Blackout or building a versatile short rifle that doesn't compromise on ergonomics or reliability, the MCX Rattler LT earns its place on the roster.
| Caliber | 300 Blackout |
| Barrel Length | 6.75 inches |
| Barrel Material | Cold Hammer Forged Carbon Steel |
| Twist Rate | 1:5 |
| Overall Length | 17.25 inches (171.5 mm) |
| Collapsed Length | 17 inches |
| Overall Width | 2.25 inches (57.2 mm) |
| Height | 7.4 inches (187.2 mm) |
| Weight | 5.8 lbs (2.6 kg) |
| Action | Semi-Automatic |
| Operating System | Short-Stroke Piston |
| Trigger Type | 2-Stage Match / Flat-Blade |
| Grip | PDW |
| Magazine Type | AR-15 Pattern |
| Magazine Capacity | 30 rounds |
| Magazines Included | 1 × 30-round Polymer Magazine |
| Accessory Rail | M1913 Picatinny |
| Flash Hider | SIG QD Suppressor-Ready (SLX/SLH Compatible) |
Yes. The rifle ships with a SIG suppressor-ready flash hider (SLX/SLH compatible) already installed and pinned. The adjustable gas piston also allows you to tune the rifle for optimal performance with a suppressor attached, whether you're running subsonic or supersonic ammunition.
Yes. The MCX Rattler LT is fully modular. The barrel is compatible with all MCX LT barrels and handguards, so you can change calibers, barrel lengths, and rail systems to suit your needs.
The rifle uses standard AR-15 pattern magazines. One 30-round polymer magazine is included in the box.
Yes. All controls—bolt catch, bolt release, and safety—are fully ambidextrous, making the rifle equally comfortable for left- and right-handed shooters.
SKU: 126817118 • Weight: 7.8oz