Sig Sauer M400 X-Series 5.56 NATO 16" Rifle 30rd - RM400SDI16BP

The Sig Sauer M400 X-Series delivers precision engineering with enhanced modularity for tactical applications and competitive shooting. This direct impingement rifle combines proven reliability with modern features that address the demands of serious shooters.

What Makes This Different

The M400 X-Series incorporates Sig Sauer's refined gas system with improved bolt carrier group materials for extended service life. The 15-inch M-LOK handguard provides 50% more mounting real estate than standard carbine-length rails, while the free-floating design eliminates barrel contact for consistent accuracy. Chrome moly steel construction in the barrel offers superior heat dissipation compared to standard steel alternatives.

Key Features

• 16-inch chrome moly steel barrel with 1:7 twist rate for optimal 5.56/.223 performance
• 15-inch M-LOK compatible handguard with full-length Picatinny top rail
• Magpul SL-K collapsible stock with 6-position carbine buffer tube
• Black anodized aluminum upper and lower receivers with Type III hard coat finish
• Standard AR-15 magazine compatibility including PMAG and USGI patterns
• Ambidextrous safety selector and enhanced trigger guard
• A2-style flash hider with 1/2x28 threading for suppressor compatibility

Field testing demonstrates consistent sub-2 MOA accuracy with quality ammunition, making this platform suitable for precision applications beyond 300 yards. The direct impingement system cycles reliably with both 5.56 NATO and .223 Remington loads, while the enhanced bolt carrier group handles rapid fire sequences without excessive fouling. Weather sealing at critical junctions maintains function in adverse conditions from desert heat to arctic cold.

Technical Specs

• Caliber: 5.56x45mm NATO/.223 Remington
• Barrel Length: 16 inches, chrome moly steel construction
• Overall Length: 32.5-35.5 inches (stock collapsed/extended)
• Weight: 6.8 pounds unloaded
• Magazine Capacity: 30 rounds (state laws may vary)
• Handguard: 15-inch M-LOK with integrated QD sling points
• Stock: Magpul SL-K synthetic with rubber buttpad
• Finish: Black anodized aluminum, black polymer components
• Made in USA with lifetime warranty coverage

This rifle represents Sig Sauer's commitment to manufacturing excellence with features that enhance both accuracy and adaptability. The combination of proven direct impingement operation with modern ergonomics creates a platform ready for immediate deployment across multiple shooting disciplines.