SIG Sauer has introduced the SIG M400 tactical carbine, an improved version of its 5.56x45mm military issue tactical carbine.

The SIG M400 uses a direct-impingement gas system and accepts parts and accessories for the original M4-style carbine.

To increase accuracy over mil-spec carbines, the SIG M400 features a tensioning device designed into the lower receiver that ensures a tight lockup and eliminates play between the upper and lower receivers. The lower receiver has all the same features as the SIG 516, such as an ambidextrous magazine release and rear quick-detach sling mount. Both receivers are machined from 7075-T6 aircraft-grade aluminum forgings and coated with a durable phosphate finish.

The upper receiver features an integrated MIL-STD 1913 top rail for mounting optics and accepts most M16/AR15-style accessories. The carbine arrives with a six-position collapsible polymer stock. An Enhanced version of the SIG M400 features all Magpul equipment.

Chambered in 5.56 NATO, the SIG M400 will be available in semi-automatic for commercial users. Three-round burst or fully automatic versions will be available for military and law enforcement. Built to full military specifications, the SIG M400 features a 16-inch chrome moly steel barrel with a chrome-lined chamber and bore. A direct-gas impingement system operates a seven-lug, rotating bolt. The muzzle is threaded ½ x 28 TPI to accept a variety of flash hiders, compensators or suppressor mounts. An M16A2 flash compensator is included.

A removable sight assembly and carry handle, 30-round magazine and hard case are standard features on this rifle.