Sturm, Ruger & Co.‘s entry into the AR market with its SR-556 and SR-762 designs prompted author Todd Burgreen to profile the new rifles for a feature in the 2015 issue of BLACK GUNS. The gas piston-operated rifles were an instant hit with Burgreen, who came away impressed with Ruger’s short-stroke piston system and its ergonomic design features.
“Ruger describes its short-stroke piston as a two-stage affair that eliminates the sharp pulse often associated with other piston ARs as the op-rod strikes the flat-faced carrier key located on the bolt carrier. Ruger’s transfer rod lies behind the gas block regulator and rests between captive springs and bushings,” says Burgreen. “The transfer rod is acted on by the piston between it and the gas port regulator, sending it rearward to work the SR-556’s action. The movement of the action provides a functional cleaning of the transfer rod. The same pattern of design is followed with the SR-556’s big brother, the SR-762.”
In examining the SR-762, Burgreen was again reminded of Ruger’s mindful implementation of a piston-driven system in its new AR designs. “Typical of the Ruger methodology, an AR design was not hastily introduced in knee-jerk fashion,” says Burgreen. “Ruger decided to enter the fray only after thoroughly exploring the topic and by designing its version of a short-stroke, push-rod, piston-driven system for the AR.”
Burgreen concluded by noting the similarities between Ruger’s 5.56mm and 7.62mm AR designs and their handling, despite their difference in caliber. “Ruger has taken its concept of the AR rifle another step forward with its SR-762 in .308/7.62mm. The SR-762 is a short-stroke gas piston AR following a similar pattern of Ruger’s SR-556 introduced previously,” says Burgreen. “The Ruger piston delivers two smaller impulses to the operating rod in lieu of the one longer, sharper impulse seen on other AR designs.”