If it ain’t broke, don’t fix it. And when it comes to Eugene Stoner’s original direct gas impingement system (DGIS), that is exactly the feeling of many AR rifle fans. In all fairness, the AR platform has been successfully serving militaries worldwide, including our own, for more than 40 years.

The SIG M400 is a traditional direct gas impingement system AR carbine with key improvements that is ready for duty use. Shown equipped with the Aimpoint Patrol Rifle Optic with 3X Magnifier.

This may explain why Sig Sauer, which originally entered the AR market with the gas piston-driven SIG516, is now offering its M400 variant, a true-blue direct gas impingement semi-auto AR carbine. Chambered in 5.56×45 mm NATO, the M400 appears and operates like a standard AR but with many unique Sig Sauer enhancements that set this rifle apart. The result is a high-quality AR ideal for law enforcement patrol use.

Quick-detach sling attachment points are machined directly into the lower of the M400, making
ambidextrous use of a sling simple and easy.

How a 150-year-old Swiss wagon manufacturer started making muskets for their nation’s military and ended up manufacturing some of the best AR rifles in the U.S. is undoubtedly a long and interesting story. Unquestionably, “Swiss-made” is synonymous with quality, and when it comes to their national defense this commitment to reliability, effectiveness and attention to detail is carried to the Nth degree.

The oval polymer handguards feature double aluminum heat shields that effectively kept the rifle cool, protecting the shooter.