LMT Defense MARS-LS Specwar 12.5 SBR 5.56 NATO — MRP-L Monolithic, Quick-Change Barrel, Ambidextrous Controls
This factory SBR pairs LMT's monolithic MRP-L Specwar upper with a fully ambidextrous MARS-LS lower, delivering a 12.5 inch, mid-length gas 5.56 NATO setup built around LMT's quick-change barrel system. It features a chrome-lined, cryogenically treated 1:7 barrel, a continuous T-marked 1913 top rail, and M-LOK slots at 3, 6, and 9 o'clock. It is an NFA item and will require a tax stamp.
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: There are some superficial scratches and blemishes present.
What’s Included
- LMT factory cardboard box with serialized label (MIDMLK125-MARS)
- LMT Monolithic Rail Platform (MRP) Operator's Manual
- Factory upper-receiver inspection tag (dated 11-07-25)
- Picatinny ladder rail covers (set)
- Two 30-round magazines: one Magpul PMAG Gen M3 (polymer) and one aluminum GI-style AR-15 magazine
The monolithic MRP-L Specwar upper uses twin barrel clamp bolts that allow fast barrel swaps while maintaining a rigid, one-piece aluminum receiver/handguard interface. The handguard provides M-LOK slots at 3, 6, and 9 o'clock with a continuous T-marked 1913 top rail. The upper is marked with U.S. Patent #8,234,808 B2 and #8,561,337 B2 and CA Patent #2,485,710.
The barrel is chrome-lined and cryogenically treated with a 1:7 twist and a mid-length gas system. A 3-prong flash hider is installed, and the barrel is threaded. Capacity is 30+1.
The MARS-LS lower delivers fully ambidextrous, mirrored controls, including the safety selector, bolt catch/release, and magazine release. It is paired with a 6-position telescoping stock and a finger-groove textured AR-15 pistol grip.
This Factory SBR configuration ships with the LMT box label dated 11/08/2025 and an upper inspection tag dated 11/07/2025. No iron sights are included.
This is an NFA item and will require a tax stamp.