One-Piece Mount
Also: Cantilever Mount
A single machined unit that combines the base and both rings into one rigid piece, often cantilevered forward for proper eye relief on short actions.
A one-piece mount fuses what would otherwise be a separate scope-base and a pair of scope-rings into one continuous block of metal. Because the ring spacing is fixed by the machining rather than set by hand, the two rings arrive perfectly aligned, which removes a common source of tube stress and helps the optic hold zero. The unit clamps to a picatinny-rail as a single piece, making installation fast and repeatable.
Many one-piece mounts are cantilevered, meaning the rings extend forward of the clamping section so the scope sits farther toward the muzzle. That extra reach is especially useful on flat-top semi-automatic rifles, where the receiver is short and the shooter needs the optic pushed forward for correct eye relief. As with any rings, the mount must be matched to the scope’s tube-diameter and torqued to specification.