This system used pressurized exhaust gases from the bore and channeled them through a port drilled in the barrel into a gas cylinder located under the barrel. The rapid build-up of propellant gases imparted rearward pressure on a long-stroke piston, driving it backwards, while an extension of the bolt carrier interacted with a helical camming slot machined into the bolt carrier, converting this linear movement into an angular velocity and forcing the bolt into a rotary motion, clearing the locking nuts and unlocking it near the end of the bolt carrier's travel. The weapon was locked into battery by two lugs on the bolt head which recessed into appropriate cavities machined into the receiver walls. Owing to its main intended use by paratroopers, the rear sight (which necessarily was rather high due to the straight stock design) was a flip-up construction. The iron sight line had a sight radius and consisted of an open-pointed-post-type front sight, and a diopter-type rear sight. It was graduated for 7.92×57mm Mauser cartridges from in increments. On later models the post front sight was hooded to reduce glare under unfavourable light conditions and add protection for the post.
