SIG Sauer M400 5.56 NATO AR-15, 16-inch Stainless Threaded Barrel, Free-Float M-LOK, UTG Sights, Magpul SL-K Stock
This customized SIG Sauer M400 stands out with a 16-inch stainless, threaded barrel, a free-float aluminum M-LOK handguard, and installed UTG flip-up sights. It includes a Magpul MOE SL-K adjustable carbine stock and a Magpul MVG M-LOK vertical foregrip. The rifle uses a direct-impingement system with a 1:8 twist barrel and comes with a 30-round Magpul PMAG.
Condition
Overall Condition: Very good condition, showing only light, superficial signs of prior handling or use.
Bore Overall Condition: Excellent - Clean, mirror finish, no signs of wear.
Bore Rifling: Excellent Rifling - Sharp lands and grooves.
Specific Condition Notes: The rifle presents in great shape with minor scratches and blemishes from prior handling.
What’s Included
- 1x 30-round Magpul PMAG polymer magazine
- UTG flip-up front sight (installed)
- UTG flip-up rear sight (installed)
- Magpul MVG M-LOK vertical foregrip (installed)
- Bolt-on M-LOK Picatinny rail section for front sight (installed)
- Magpul MOE SL-K adjustable carbine stock (installed)
The M400 platform uses a direct-impingement gas system with a low-profile gas block for a clean, streamlined front end. The aluminum receivers wear a matte black finish, and the upper includes a forward assist, brass deflector, and dust cover. A MIL-STD-1913 top rail with T-markings provides consistent, repeatable positioning for mounted accessories.
The 16-inch stainless barrel is marked 5.56 NATO with a 1/8 twist. It is threaded and fitted with a 3-prong flash hider and crush washer. This setup supports standard muzzle device compatibility while maintaining a stainless, silver-finished profile.
The free-float aluminum handguard features elongated M-LOK slots and no continuous top rail. A bolt-on M-LOK Picatinny section is installed at the front to mount the UTG flip-up front sight, with the matching UTG rear sight on the upper receiver. A Magpul MVG M-LOK vertical foregrip is installed for added control.
Furniture includes the Magpul MOE SL-K adjustable carbine stock on a carbine receiver extension, with a length of pull of 10.5 to 13.5 inches. The rifle retains the SIG SAUER polymer pistol grip and ships with a 30-round Magpul PMAG. Receiver markings include SIG SAUER SIGM400 on the upper and SIG SAUER INC, NEWINGTON NH, USA on the lower.