SIG SAUER MCX SPEAR-LT IR Semi-Auto SBR RMCX556N11BIRSBR — Description

The SIG SAUER MCX SPEAR-LT IR RMCX556N11BIRSBR is a premium 5.56 NATO semi-automatic SBR (Short-Barreled Rifle) built on SIG Sauer’s advanced MCX SPEAR-LT modular rifle platform. Designed for compact performance and versatility, this configuration combines an 11.5-inch barrel, Coyote Tan finish, folding/collapsible stock system, and the proven short-stroke gas piston operating system of the MCX family.

The MCX SPEAR-LT represents the latest evolution of the MCX platform, incorporating a lightweight handguard, improved modularity, fully ambidextrous controls, and compatibility with modern accessories. The rifle features a free-floating M-LOK handguard, optics-ready upper receiver, and SIG Sauer’s match trigger system for enhanced control and precision.

Built for users who require a compact and adaptable rifle platform, the SPEAR-LT IR SBR offers the maneuverability of an 11.5-inch configuration while maintaining the reliability benefits of a piston-driven action. The folding stock design allows for easier storage and transport, while the 30-round magazine provides standard-capacity firepower in compatible configurations.

SIG SAUER MCX SPEAR-LT IR RMCX556N11BIRSBR — Specifications

Manufacturer: SIG SAUER
Model: MCX SPEAR-LT IR SBR
Model Number: RMCX556N11BIRSBR
Caliber: 5.56 NATO (.223 Remington compatible)
Action: Semi-automatic
Operating System: Short-stroke gas piston with rotating bolt
Platform: SIG MCX SPEAR-LT modular rifle system
Barrel Length: 11.5 inches
Barrel Twist Rate: 1:7″
Barrel Type: Cold hammer forged barrel
Receiver Material: Aluminum
Finish: Coyote Tan anodized finish
Stock: Collapsible/folding stock with cheek rest
Handguard: Free-floating M-LOK handguard
Trigger: SIG SAUER 2-stage Match-Duo trigger
Magazine Type: AR-15 / STANAG compatible detachable magazine
Magazine Capacity: 30 rounds
Controls: Fully ambidextrous controls
Charging Handle: Non-reciprocating side charging handle and rear charging handle configuration
Muzzle Device: SIG suppressor-ready flash hider
Sights: Optics-ready Picatinny rail
Weight: Approx. 6.9 lbs (without magazine)
Overall Length: Approx. 29.25 inches extended (configuration dependent)

Key Features

• 5.56 NATO chambering
• 11.5-inch SBR configuration for compact handling
• Short-stroke gas piston system for reliable cycling and reduced fouling
• Coyote Tan finish
• Folding/collapsible stock system
• Fully ambidextrous bolt catch, magazine release, and safety controls
• SIG 2-stage Match-Duo trigger
• Free-floating M-LOK handguard
• Cold hammer forged barrel
• Modular MCX SPEAR-LT architecture
• AR-15 magazine compatibility
• 30-round magazine capacity
• Optics-ready upper receiver

Package typically includes:

• SIG SAUER MCX SPEAR-LT IR 5.56 NATO SBR
• Folding/collapsible stock assembly
• 30-round magazine (configuration dependent)
• Owner’s manual
• Safety documentation