Industry Watch
Zenith Firearms’ MRDS Rifles Bring Roller-Delayed Blowback Into the AR Era
Billet receivers, AR-compatible controls, and modular rails meet a classic operating system
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✍️By ZRIntel Editorial Team📍Afton, VA
Zenith Firearms has unveiled its Modern Roller-Delayed System (MRDS), a new family of rifles that combine the proven roller-delayed blowback operating system with modern AR-style compatibility and modular features. Based in Afton, Virginia, the company transitioned from importing Turkish-made HK-pattern firearms to building its own line in-house. The MRDS represents Zeniths effort to merge historical strengths with 21st-century expectations for modularity and customization. At first glance, MRDS rifles resemble modern sporting rifles. Both the upper and lower receivers are machined from billet aluminum. The lower accepts AR-15 compatible fire-control groups and pistol grips, making upgrades straightforward. Ambidextrous controls are standard, including safety selector, magazine release, and bolt release. Standard AR magazines are used, and the rifles ship with an Amend2 30-round magazine in 5.56 NATO and .300 Blackout chamberings. Internally, the rifles are built around steel guide rails and a trunnion for the rollers. The spring-loaded dustcover and polymer shell deflector function like those found on ARs but retain the HK-style roller system at the core. A free-floating barrel design ensures accuracy, as no gas system contacts the barrel from chamber to muzzle. The aluminum handguard features extensive M-Lok slots and a Picatinny rail for optics, providing over 19 inches of mounting space on rifle-length models. The system stays true to its heritage with a dual-roller delayed blowback action, prized for smooth recoil impulse and reduced bolt mass. The charging handle recalls HK tradition with its ability to lock to the rear for the familiar HK slap, while also being reversible to either side. Barrel options range from 7.5 inches to 16 inches, with rifles chambered in 5.56 NATO (ZF-56), .300 Blackout (ZF-300), and 7.6239 mm (ZF-39). A 350 Legend hunting variant (ZF-350) with a 20-inch barrel further showcases the systems flexibility. Pricing spans $1,669 to $1,950. Field testing of the ZF-56 with a 16-inch barrel showed flawless reliability across brass and steel-cased ammunition. Brass cases bore the expected fluted-chamber marks and dents from the deflector, making them unsuitable for reloading, but operation remained smooth. The single-stage trigger broke just under six pounds with a positive reset. Takedown mirrors AR rifles: two pins separate the receivers, and the bolt group withdraws from the rear. Maintenance is simplified by the absence of a gas system to clean. Each rifle ships in a TSA-compliant, lockable hardcase, a notable addition at this price point. Zenith is planning future MRDS expansions. The ZR-9 and ZR-10, chambered in 9 mm and 10 mm Auto respectively, will feed from Glock-compatible magazines and are slated for release at SHOT Show 2026. With compact barrels and light weights, these pistol-caliber carbines are positioned for civilian, law enforcement, and recreational use. Barrels will be cold hammer-forged and threaded, supporting common muzzle devices. The company has also suggested a larger-frame MRDS scaled to 7.62 NATO could be in development. By combining the roller-delayed action with AR compatibility, Zenith has carved out a niche that appeals both to traditionalists who appreciate the HK heritage and to modern shooters demanding modularity. Whether in tactical, hunting, or recreational settings, the MRDS rifles represent a reimagining of a classic system for todays market.