SIG Sauer M400 TREAD 5.56 NATO Semi-Auto AR-15 Rifle, 16 inch Threaded Barrel, Free-Float M-LOK Handguard, Magpul MOE SL-K Stock, 30+1
This SIG Sauer M400 TREAD is a 5.56 NATO, direct-impingement AR-15 featuring a 16 inch threaded barrel, a free-floating aluminum M-LOK handguard, and a flat-top T-marked upper receiver rail. It comes with practical upgrades installed, including a Magpul RVG vertical foregrip and a B.A.D.-style extended bolt-release lever, along with a Magpul MOE SL-K adjustable stock. The bore is rated excellent, and the factory box confirms SKU RM400-16B-TRD.
Condition
Overall Condition: Good condition, showing some signs of prior use and handling.
Bore Overall Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: There are scuffs, finish wear, and scratches consistent with prior use and handling.
What's Included
- SIG Sauer factory cardboard box with RM400-16B-TRD label
- Magpul RVG vertical foregrip (installed)
- M-LOK accessory Picatinny rail section (installed)
- SIG Sauer TREAD M-LOK emblem panel (installed)
- Magpul B.A.D. Lever extended bolt-release (installed)
- 1x 30-round Magpul PMAG polymer magazine
The M400 TREAD platform pairs aluminum receivers with a free-floating aluminum M-LOK handguard that deletes the top rail for a streamlined feel. The flat-top, T-marked Picatinny upper receiver provides a continuous mounting surface, and the rifle includes a forward assist, dust cover, selector pictograms, and a SIG logo on the magwell.
The 16 inch barrel is threaded and capped with an A2-style flash suppressor. The bore is clean with a mirror finish and sharp rifling, supporting the excellent rating noted in the item details.
Ergonomics and controls include a Magpul MOE SL-K adjustable 6-position stock, a polymer pistol grip with SIG SAUER texturing and logo, and a manual safety. A single-stage, polished trigger is specified. An installed Magpul B.A.D.-style extended bolt-release lever enhances bolt control.
Accessory setup features a Magpul RVG vertical foregrip mounted via an M-LOK rail section, plus a yellow TREAD emblem panel fitted to an M-LOK slot. The rifle uses the AR-15/STANAG detachable magazine interface and comes with one 30-round Magpul PMAG for a 30+1 capacity.
Factory identification is confirmed by the box label showing SKU RM400-16B-TRD. This U.S.-made rifle has a black finish throughout and maintains the TREAD series feature set noted above.