The M400 X-series features a free-floating M-LOK handguard, Magpul SL-K 6-position telescoping stock, Sig Flat Match Grade trigger, 16" Chrome Moly barrel, and a 7075 T-6 aluminum receiver with a black hardcoat anodized finish.
| Series | X-Series |
| Model | M400 |
| Caliber | 5.56x45mm NATO |
| Barrel Length Range | 16" to 16.99" |
| Gun Platform | AR-Style |
| Operating System | Direct Impingement |
| Stock Finish Group | Black |
| Capacity | 30+1 |
| Stock Material | Synthetic |
| Action | Semi-Auto |
| OAL | 33.50"- 36.75" |
| Hand | Right Hand |
| Sights | Optic Ready |
| Barrel Finish | Black FNC |
| Muzzle | Hybrid Compensator / Flash Hider |
| Twist | 1:7" |
| Magazine Type | AR-15 |
| Grips | Black Polymer |
| Handguards | 15" M-LOK |
| Receiver Material | Aluminum |
| Safety | Ambidextrous |
| Thread Pattern | 1 / 2"x28 |
| Stock Description | Magpul SL-K |
| Barrel Description | Chrome Moly Steel |
| Barrel Length | 16" |
| Max Capacity | 30 |
| Receiver Finish | Black Anodized |
| Trigger | Flatblade Match |
| Weight | 7 lbs |
| Stock Finish | Black |
