The Sig Sauer MCX Rattler LT SBR, 5.56mm, 7.75-Inch, Black (brand part no. RMCX-556N-7B-LT-SBR) is a .223 REM/5.56 NATO short-barrel rifle built around a 7.75-inch barrel. It runs a semi-auto action and feeds from a 30-round magazine, giving shooters a compact platform for close-quarters use. Sig Sauer builds it as a complete, transferable short-barrel rifle.

Key Specifications

• Chambered in .223 REM/5.56 NATO.
• Wears a 7.75-inch barrel, the defining feature of this short-barrel rifle.
• Feeds from a 30-round magazine.
• Operates as a Semi-Auto platform for reliable cycling.
• Equipped with a Manual Safety for controlled operation.
• Measures 25.9 inches overall.
• Cut with a 1:7 rate of twist.
• Equipped with Optic Ready.

Frequently Asked Questions

Is this an NFA item? Yes. As a short-barrel rifle, it's a Title II firearm requiring an approved ATF Form 4 and transfer through an NFA-licensed dealer.

What caliber does it fire? .223 REM/5.56 NATO.

How many rounds does the included magazine hold? 30 rounds.

Buy the Sig Sauer MCX Rattler LT SBR, 5.56mm, 7.75-Inch, Black

This is a Title II item regulated under the National Firearms Act. Purchase requires an approved ATF Form 4, no federal transfer tax, and transfer through a licensed NFA (SOT/Class 3) dealer, with an extended federal approval wait before delivery. Order through Sig Sauer‘s short-barrel rifles lineup and our Lubbock, Texas team will walk you through the transfer process.