A Nightforce Compact 2.5-10x Riflescope was used on the author's…

A Nightforce Compact 2.5-10x Riflescope was used on the author’s test LMT 6.8 SPC rifle

Rifle manufacturer Lewis Machine & Tool Company (LMT) has been on a tear. Their 7.62mm Modular Weapon System LM308MWS was adopted by the British Army as the L129A1. The Chicago Police department, one of the oldest modern police departments in the world, has approved the use of the LMT CQB for patrol duty. And even TV’s Brian “Pig Man” Quaca, hog hunter supreme, has signed on to use LMT rifles on his relentless mission of pig eradication. How do you top that? By giving owners of your MRP weapons the ability to upgrade their rifles to one of the hottest AR calibers in gas-piston trim.


The 6.8mm Special Purpose Cartridge (SPC) was created by Remington Arms with input from U.S. SOCOM to increase the power of the issue AR-based family of rifles, without scaling up to a new gun for the .308/7.62mm round. With the same overall length as a 5.56x45mm round but propelling a 115-grain bullet at 2,500 fps, the 6.8 SPC should have been an instant hit, but it has taken nearly a decade to win over the AR community.

One reason the 6.8 SPC was a slow starter was because there were literally millions of rifles already chambered for .223 and 5.56mm NATO. Many gunowners did not want to go through the hassle of re-barreling their rifle and getting new magazines and bolt carrier groups to work with the SPC’s .30 Remington case head. But owners of the LMT series of MRP rifles have no such qualms: the Defender Monolithic Rail Platform (MRP) pioneered by LMT allows easy swapping of barrels by loosening the two star-head bolts.


The CQB MRP was created in response to the growing demand for quick-change barrel systems. Karl Lewis, president of LMT, designed the MRP as a true user-interchangeable barrel system based on a lightweight upper receiver machined from a single piece of aluminum. With the MRP, all play between the forend and the receiver is eliminated, creating a solid, unitized base for optics and night-vision systems and supplying a feel that standard M4s cannot match. LMT replacement barrels with either full-length direct-gas tubes or short-stroke pistons can be interchanged as long as the appropriate bolt carrier group is used. Now, civilian, military and police MRP owners can opt to power up with 6.8 barrels in either gas system.

The new CQB MRP 6.8 SPC Piston Conversion Kit comes with a gas piston 16-inch chrome-lined barrel with a 1-in-10-inch twist rate, a GP semi-auto bolt carrier group, a heavy-duty H2 buffer charging-handle assembly and a 25-round magazine.

Although they are the same overall length, the 6.8 SPC and 5.56mm NATO rounds require two different magazines

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  • Frank

    So what is going on at Simi Valley? Is it for PD? Or a field test?