The first attempts to improve the performance of the 16-inch gun at Barbados were made in 1964, primarily by increasing the length of the barrel. In 1962, the Ballistic Research Laboratory increased the barrel length of a 5-inch gun system by welding a second section of barrel to the muzzle of the first barrel, lengthening the barrel to 8.9 meters. The resulting gun system demonstrated a higher muzzle velocity at muzzle exit since the longer barrel allowed the propellant gases to push on the projectile for a longer period of time. In September 1964, a ten-calibers extension was added to the 16-inch gun based on BRL's experiment with the 5-inch gun. However, while increased velocity and altitude was recorded for test flights, the extension failed in December after the eleventh shot was fired. In 1965, a successful extension of the 16-inch gun was established after enlarging the gun pit to accommodate the large size of the equipment. The extension almost doubled the length of the gun to 120 feet and weighed nearly 100 tons, making the 16-inch Barbados gun the largest operational artillery piece in the world at the time.