The system keeps hot carbon fouling and waste gases out of the receiver area, which "virtually eliminates malfunctions that are common to direct impingement gas systems," according to H&K.
Assemblies and accessories developed for the 416/417 will be carried over, including the free-floating quad-rail system that can accommodate a variety of accessories, sights and lights.
Cold-hammer-forged barrels can handle more than 20,000 rounds before the operator would notice degradation in accuracy or muzzle velocity, according to H&K.
Other accessories include various-sized pistol grips, fully interchangeable upper receivers and an adjustable buttstock with a storage compartment for extra batteries or other gear. Magazines for the MR556A1 are available in 10- or 30-round steel, while the MR762A1 arrives with 10- or 20-round polymer capacity.
The pair of carbines will be produced at a new 70,000-square-foot manufacturing facility located in Newington, N.H., and will retail for $2,900 each.