SIG Sauer M400 TREAD 5.56 NATO AR-15, 16 in Stainless Free-Float Barrel, Geissele Trigger, ROMEO5 Red Dot
This SIG Sauer M400 TREAD stands out with a stainless, free-floated 16-inch barrel, a mid-length gas system, and an ODIN Works Ragna M-LOK handguard. It has a Geissele trigger installed for a refined pull and comes outfitted with a SIG SAUER ROMEO5 red-dot on a riser mount. The rifle features an ambidextrous safety, adjustable 6-position stock, and practical upgrades like an M-LOK QD sling socket.
Condition
Overall Condition: Good condition, showing some signs of prior use and handling.
Bore Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: There are visible handling marks from previous use on external surfaces. Please review the photos for a clear view of these areas.
What's Included
- SIG SAUER ROMEO5 red-dot sight with MOTAC motion-activation and 2-MOA dot (installed)
- Riser mount for ROMEO5 (installed)
- Sling
- M-LOK QD sling socket (installed on handguard)
- Geissele trigger (installed)
- 1x 30-round Magpul PMAG polymer AR-15 magazine
The M400 TREAD platform delivers the familiar AR-15 layout with semi-automatic, direct-impingement operation and a mid-length gas system. This configuration supports smooth function with 5.56 NATO while preserving the TREAD series' clean, modern feature set.
The 16-inch stainless steel barrel is free-floated for consistency and uses a 1:8 twist to stabilize a broad range of 5.56/.223 bullet weights. A three-prong flash hider is fitted at the muzzle. The Geissele trigger installed on this rifle provides a precise, consistent trigger press.
The aluminum ODIN Works Ragna handguard is free-float and M-LOK compatible. An M-LOK QD sling socket is installed for quick sling attachment. Controls include an ambidextrous safety selector, with a forward assist and ejection-port cover present.
Furniture consists of an adjustable 6-position stock with a 10.5-inch length of pull and a SIG-branded polymer pistol grip. The receiver is aluminum with a matte black hard-anodized finish, and it carries factory markings: 'SIG SAUER SIGM400' and 'SIG SAUER INC, NEWINGTON, NH, USA'.
Included optics are ready to use: a SIG SAUER ROMEO5 red-dot sight with a 2-MOA red dot and MOTAC motion activation, mounted on a riser for a straightforward sight picture. Capacity is 30+1, and a 30-round Magpul PMAG is included.