The GSh-18 is a rotating-barrel, short-recoil, locked-breech pistol with 10 locking lugs spaced equally around the barrel, the large locking surface area resulting in a strong lockup, making it suitable for high-velocity ammunition loads. The GSh-18 may be employed using standard 9x19mm Parabellum rounds, but was designed for the high velocity, Russian armour-piercing 7N31 9x19mm round. The pistol incorporates a pre-set striker. The slide and working parts are steel, and the weapon has a polymer frame. Two different designs of grip have been observed. The magazine capacity is 18 rounds, and an additional round may be carried in the chamber. The magazine release is reversible for left-handed shooters and the ejector doubles as a loaded chamber indicator. The magazines are a double stack design common to many modern handguns. The GSh-18 pistol contains only 17 parts (by comparison, the Glock 17 contains 34 parts).