Sig Sauer M400 TREAD 5.56 NATO AR-15, 16 in Stainless Threaded Barrel, Mid-Length Gas, Free-Float 15 in M-LOK, 30+1
This Sig Sauer M400 TREAD is a USA-made AR-15 chambered in 5.56 NATO with a 16-inch stainless steel threaded barrel and a 1:8 twist. It features a mid-length gas system, a free-float 15-inch M-LOK aluminum handguard with a stylized flag engraving, and arrives with a detachable vertical foregrip and a pair of 1-inch scope rings already installed. It is in excellent condition with a clean, mirror-bright bore.
Condition
Overall Condition: Excellent condition, showing only faint signs of any prior use or handling.
Bore Overall Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: This rifle shows very mild wear from light prior use and careful handling.
What’s Included
- Pair of 1-inch scope rings (installed)
- Detachable vertical foregrip (installed)
- 1x 30-round Magpul PMAG polymer AR-15 magazine
The M400 TREAD platform combines a direct-impingement action with a flat-top Picatinny upper receiver, forward assist, dust cover, and case deflector. Controls include a manual safety selector with pictogram legends, and the rifle uses the standard STANAG/AR-15 detachable magazine interface for broad magazine compatibility.
The 16-inch stainless steel barrel is threaded at the muzzle and fitted with a factory three-prong flash hider. A 1:8 twist provides versatile stabilization across common 5.56/.223 projectile weights. The mid-length gas system uses a low-profile gas block for smooth cycling.
An aluminum free-float M-LOK handguard measuring approximately 15 inches runs nearly the full length of the barrel, enhancing accessory mounting space. The left side of the handguard is engraved with a stylized flag motif, adding a distinctive visual detail.
Furniture includes a Magpul-branded collapsible carbine stock and a SIG-branded textured polymer pistol grip. Installed accessories include a detachable vertical foregrip and a pair of 1-inch scope rings on the upper receiver rail, and the package ships with a 30-round Magpul PMAG magazine.