SIG M400

The SIG M400 is a firearm manufactured by SIG SAUER. The rifle is based on the earlier 5.56mm AR-15 and M16.

Operating mechanism
The SIG M400 is a semi-automatic firearm/rifle, intended for civilian and law enforcement markets. It fires from a closed bolt and use a direct gas impingement system.

Features
Ergonomically, the SIG M400 is patterned after the AR15 type rifle. It has a safety lever on the left side, to be used by the thumb of the shooting hand. The front gas block is railed to accept the front sight with a flip-up sight post. M400 models are equipped with an M16-A2 style bird-cage flash hider.

All models accept AR15 style box magazines. These magazines are constructed in 5, 10, 20, and 30 round variants. The rifle is hammer-fired with a single stage trigger.

The M400 has a telescoping skeletonized buttstock. The ACE-style stock moves forward and rearward in 6 positions. A spring loaded release underneath the buffer tube area locks into each position.