The LMT MRP-L M-LOK SPECWAR 5.56mm 11.5” Assembled Upper Receiver (LMT part no. L7Z1A) is a complete Mars-L monolithic upper built to the SPECWAR configuration LMT supplies for special operations-style carbines, chambered in 5.56mm with an 11.5-inch barrel. The M-LOK handguard slots give a lighter, more modular mounting option than the quad-rail MRP-L variants while keeping the same one-piece monolithic rail construction. This length and configuration is a proven duty and SBR-length setup for close-quarters and vehicle-borne operations. LMT assembles this upper to the same standard used on its SOPMOD and MARS-L contract rifles.

Key Specifications

• Measures 11.5 inches, a proven duty-standard length for short-barrel AR15 builds.
• Chambered for 5.56mm, the standard AR15 platform cartridge.
• Built on the Mars-L monolithic rail platform with M-LOK accessory slots.
• Sold fully assembled, ready to mate to a compatible AR15 lower.
• Uses M-LOK accessory slots rather than a full quad rail, saving weight.
• Eliminates the barrel nut interface entirely, helping hold zero on mounted optics.
• Compatible with mil-spec AR15 lower receivers accepting a standard pivot and takedown pin.

Frequently Asked Questions

What does SPECWAR configuration mean on this upper? It refers to the special operations-style setup LMT builds, combining the Mars-L monolithic rail with an 11.5-inch barrel and M-LOK handguard.

Is an 11.5-inch barrel NFA-regulated on a rifle build? Barrels under 16 inches on a rifle-configured receiver generally require NFA registration as a short-barreled rifle; verify your build’s configuration before assembly.

Buy the LMT MRP-L M-LOK SPECWAR 5.56mm 11.5-inch Assembled Upper Receiver

Shop the LMT Defense SPECWAR upper in our AR15 uppers selection, with fast, insured shipping from our Lubbock, Texas gun shop.