The Sig Sauer M400 SDI X in .223 Rem/5.56 NATO (brand part no. RM400-SDI-16B-FDE) pairs a 16-inch barrel with a 1:7 twist, finished in FDE with a Sig M-PUL adjustable stock. Sig Sauer fits a lever-action-style safety and ships this rifle with an included 30-round polymer magazine. The rifle measures 46.2 inches overall and ships at approximately 9.7 pounds. Among AR-platform rifles in the AR rifles category, the M400 SDI X favors shooters who want a Sig-built AR-15 in a distinctive FDE finish.

Key Specifications

• Chambered in .223 Rem/5.56 NATO.
• Rifled at a 1:7-inch twist.
• Features a 16-inch barrel.
• Stock is a Sig M-PUL adjustable design.
• Ships with an included 30-round polymer magazine.
• Includes a lever-action-style safety.
• Overall length is 46.2 inches.
• Ships at approximately 9.7 pounds.
• Finished in FDE.

Frequently Asked Questions

What magazine ships with this rifle? An included 30-round polymer magazine.

What stock does this rifle use? A Sig M-PUL adjustable stock.

Buy the Sig Sauer M400 SDI X, FDE

A Sig-built AR-15 in a distinctive FDE finish is exactly what the M400 SDI X delivers. As soon as it’s ready to ship, order it from our Lubbock, Texas gun shop for fast, insured shipping to your FFL.