It was designed to be as short as possible to avoid problems found on high-speed aircraft when the guns were pointed into the airstream.[1] In the late 1940s and the early 1950s tests with defensive bomber turret cannons resulted in problems caused by the air flow affecting the weapons' barrel.Among these were the widely used Nudelman-Rikhter NR-23, found in many bomber installations, with barrels that extended far past their mounting points.This created a gun with shorter overall length, and greatly improved the balance, with the center of gravity almost directly under the middle of the barrel.This leads to the traditional cartridge layout with the bullet or shell at the front, and a tapering cylindrical casing behind it.As the round is pushed forward, the tapering shape of the bullet and casing guides it into the center of the chamber.To accomplish this, GSKB-398 (now GNPP PRIBOR) designed a round with the bullet completely enclosed in a galvanized steel casing, which was tapered to a bullet-like ogee at the rear and tipped by the electrically-fired primer.This anti-aircraft ammunition was originally shipped to Syria and ended up in Lebanon, where it was found by the Israeli army.