The Mark 12 5"/38-caliber gun was a United States dual-purpose naval gun, but also installed in single-purpose mounts on a handful of ships. The 38-calibers long barrel was a mid-length compromise between the previous United States standard 5-inch/51 low-angle gun and 5-inch/25 anti-aircraft gun. The increased barrel length provided greatly improved performance in both anti-aircraft and anti-surface roles compared to the 5-inch/25 gun. However, except for the barrel length and the use of semi-fixed ammunition, the 5"/38 gun was derived from the 5"/25 gun. Both weapons had power ramming, which enabled rapid fire at high angles against aircraft. The 5"/38 entered service on USS Farragut, commissioned in 1934, the first new destroyer design since the last Clemson was built in 1922. The base ring mount, which improved the effective rate of fire, entered service on USS Porter, commissioned in 1936.