I tested the piston-driven MRP with a chrome-plated and manganese-phosphate finished 16.1-inch barrel with semi-automatic bolt carrier, as well as a full-automatic carrier provided for use with a 12-inch barrel. To test the piston-operated MRP, I used 300 rounds of Silver State Armory 5.56x45 mm NATO ammunition. Most was fired on full-automatic. No malfunctions were encountered. I tested the same 4X 20 mm ACOG with both Silver State Armory as well as Black Hills 77-grain OTM ammunition. This particular rifle grouped the Silver State Armory ammunition slightly better. Groups measured just less than 1.75 inches at 100 yards. The Black Hills average was slightly more than 2 inches.

LMT’s MRP Accessories
Both direct-gas and piston-operated LMT rifles feature numerous proprietary accessories, including a six-position SOPMOD stock, which is used as part of the SOPMOD kit as well as on all Navy Mk 18 Mod 0 CQB rifles. Dual battery storage compartments and a smooth triangular shape give the stock a comfortable cheekweld when shooting. A removable rubber buttpad wraps around the buttplate, and two fittings accept QD sling adapters. The SOPMOD stock is tight on the receiver extension to help eliminate wobble. The pistol grip is the comfortable Ergo Grip, which has found great acceptance with the SOCOM Mk 12 Special Purpose Rifles. The guns also included ambidextrous selector levers, which is a great enhancement for left-handed shooters but is useful under some circumstances for right-handed shooters as well.

The upper receivers are equipped with the LMT back-up iron sights (BUIS), which are also standard-equipment on the Navy Mk 18 Mod 0. The rear sights are fully adjustable for windage and elevation, and features dual apertures for both short- and long-range shooting, while the front sights have the traditional triangular shape and are removable. The charging handles have enlarged latches that proved easy to grasp.

My overall impression of the LMT MRP system was outstanding. Being able to change out barrels not only for length, but also for caliber, and change over the operating system with the turn of two screws is amazing. The fit and finish of the rifles were top-rate, and there was little difference in feel between the impingement and the piston-operated rifles.

With its quality of manufacturing, variety of chamberings and unique design, the LMT MRP takes the aging AR platform into another realm.