SIG Sauer SIGM400 TREAD 5.56mm AR-15 Rifle – 16-Inch Stainless Barrel, Ambidextrous Controls, Threaded 1/2-28
The SIGM400 TREAD combines proven AR-15 function with SIG Sauer’s factory upgrades. A mid-length gas system softens recoil, the 16-inch stainless barrel is already threaded 1/2-28 for muzzle devices, and ambidextrous controls come standard. Built on 7075-T6 forged receivers and supported by the TREAD accessory line, this rifle arrives ready for range duty or tailored customization.
Condition
Overall Condition: Very good – Light, superficial signs of prior handling or use.
Specific Condition Notes: This rifle shows mild handling marks consistent with careful range use; the matte black finish remains uniform with no notable scratches or dings.
Bore Condition: Excellent – Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent – Sharp lands and grooves.
What’s Included
- 1 × 32-round polymer AR-15 magazine marked “32 ROUNDS”
The mid-length gas system reduces recoil impulse and parts wear compared with standard carbine-length setups, helping shooters stay on target during rapid strings.
A free-float aluminum M-LOK handguard keeps accessories solid while eliminating barrel contact for repeatable accuracy. Its two-screw design lets owners swap handguards without a vise.
The 16-inch stainless steel barrel features a 1:8 RH twist that stabilizes the full range of 5.56 projectiles. Factory 1/2-28 threads accept common flash hiders, compensators, or suppressor mounts.
Ambidextrous safety selector and magazine release make the rifle equally accessible to left- or right-handed users. A single-stage trigger offers a familiar, consistent pull.
Forged 7075-T6 receivers, a six-position telescoping stock, and textured polymer pistol grip round out a durable, user-focused package. Serial prefix “20L” places production in 2020–2021.