1. Home
  2. AR-15
  3. Rifles
  4. RM400-SDI-16B-FDE

Sig Sauer M400 SDI XSeries 5.56 NATO 16" - AR-15 Rifle

Manufactured by Sig Sauer
SKU: RM400-SDI-16B-FDE
MPN: SIRM400SDI16FDE
Manufactured by Sig Sauer
(0) No Reviews yet
$1,599.99

Out of Stock

For individual Officer, First Responder, and Military pricing please make sure you are logged in. for details

Items that are regulated by the ATF have restrictions and requirements: 
•Your entire order will ship only to a Federal-Firearm License holder.
•Please contact your local FFL prior to placing your order to ensure they are still accepting transfers.
•A copy of your order/invoice as well as the current FFL license for your local dealer must be emailed to ffl@primaryarms.com.

Details

Details

A solid 5.56 NATO AR-15 without the fluff: the Sig Sauer M400 SDI XSeries 5.56 NATO 16" focuses on reliable function, practical configuration, and durable construction in a package ready to use straight from the box.

A semi-automatic AR-15 rifle chambered in 5.56 NATO, the Sig Sauer M400 SDI XSeries 5.56 NATO 16" combines direct impingement operation with standard AR-15 architecture for straightforward reliability.

Consistent Cycling: The direct impingement system delivers consistent cycling across the standard 5.56 NATO ammunition spectrum without requiring frequent cleaning or special maintenance.

Versatile Configuration: With a 16" barrel and standard AR-15 ergonomics, this rifle fits the broadest possible range of users and use cases without compromise in any single area.

Upgrade-Friendly Platform: Everything on this AR-15 is standard — stocks, grips, handguards, triggers, and optic mounts can all be upgraded without specialized tools or gunsmithing knowledge.

Weather-Resistant Finish: The Type III Hardcoat Anodized finish provides lasting protection against corrosion and everyday wear — reliable function from the first range trip to the last.

  • Caliber: 5.56 NATO
  • Barrel Length: 16"
  • Gas System: Direct Impingement
  • Handguard: Free-Float
  • Muzzle Threading: 1/2x28
  • Magazine Capacity: 30 Round
  • Finish: Type III Hardcoat Anodized
  • Origin: Made in the USA

Drop-in compatible with mil-spec AR-15 lower receivers. Takes standard STANAG magazines chambered in 5.56 NATO and works with the full range of AR-15 accessories and aftermarket upgrades.

The upper and lower receivers are constructed from 7075 aluminum with a Type III Hardcoat Anodized finish — a durable combination that resists corrosion and maintains tight tolerances over an extended service life.

Practical for home defense, recreational range use, and entry-level competition. Suits both first-time AR-15 buyers and experienced shooters looking for a dependable utility rifle.

SIG SAUER is trusted by the U.S. military and law enforcement agencies worldwide. Their AR-15 lineup delivers the same premium quality and engineering that earned SIG that trust. Made in the USA.

See More

Specifications

ActionSemi-Auto
Barrel Length16
BrandSig Sauer
Caliber Gauge5.56 NATO
ColorFlat Dark Earth
Magazine Capacity30
ModelM400 SDI XSeries
Muzzle DeviceFlash Hider
Thread Pattern1/2 X 28
Twist Rate1:7
Weight7 lbs.
California Prop 65 warning

 WARNING: This product can expose you to chemicals, which are known to the State of California to cause Cancer and Reproductive Harm. For more information go to www.P65Warnings.ca.gov.

Ratings & Reviews

No reviews available

Be the first to Write a Review