SIG SAUER M400 SDI for Sale

Quick Look

The SIG Sauer M400 SDI is a modern AR-style rifle introduced to meet rigorous duty and personal defense needs. It emphasizes modularity and rugged reliability, built on a direct impingement system for practical performance. This model holds a respected place among mid-weight rifles favored by law enforcement and enthusiasts alike.

Why It's a Top Choice

• Reliable SIG direct impingement action
• Modular handguard and accessory options
• Precision barrel with reliable accuracy
• Ergonomic design for comfortable handling
• Good factory warranty and support

Key Variants

M400 SDI Patrol

A compact version with a 16" barrel ideal for patrol and duty use.

M400 SDI Piston

Featuring a piston system for reduced fouling, suited for extended use.

M400 SDI Carbine

Standard full-size 18" version built for versatility and range work.

Competitor Comparison Table

Feature	M400 SDI	Ruger AR-556	Smith & Wesson M&P15 Sport II
MSRP	$1,000–$1,200	$700–$900	$800–$1,000
Capacity/Size	30 rounds / 16–18" barrel	30 rounds / 16" barrel	30 rounds / 16" barrel
Weight	6.8 lbs	6.5 lbs	6.5 lbs
Optics-Ready	Yes, Picatinny rail	Yes, Picatinny rail	Yes, Picatinny rail
Trigger Type	Mil-spec single-stage	Mil-spec single-stage	Mil-spec single-stage
Notable Pro	SIG quality control and precision	Affordable price point	Strong aftermarket support
Notable Con	Higher price than entry ARs	Basic furniture and finish	Slightly heavier than peers

Best Use Cases

• Duty and law enforcement applications
• Personal defense and home protection
• Range training and marksmanship practice
• Light hunting where legal and appropriate
• Collectors valuing SIG design and quality

FAQs

Can I use standard AR-15 magazines with the SIG Sauer M400 SDI?

Yes, the M400 SDI accepts standard AR-15 magazines, facilitating wide aftermarket magazine compatibility.

What barrel lengths are available for the M400 SDI?

Common barrel lengths include 16 and 18 inches, balancing maneuverability and ballistic performance.

How does the direct impingement system affect maintenance?

Direct impingement requires regular cleaning but offers proven reliability and reduced weight compared to piston systems.