rotating the mount on its stand). This mount was the standard installation on battleships, cruisers, early destroyer leader (, ) classes (these mounts on the DL's were single-purpose/anti-surface ship only), and later destroyers (starting with the ). It was also used on the island (starboard) side of the s. Enclosed single All enclosed single mounts sat on a base ring stand, and had an upper handling room. The enclosed single mount was used on some early destroyer classes ( (1937) up to and including the (1942)), but by the end of World War II, it was mainly found on the many minelayers and auxiliaries which were developed from the older classes of destroyers, as well as on most of the destroyer escorts, and many large auxiliaries (repair ships, destroyer tenders, etc.). Open single base ring mount Open mount with Upper-Handling Room. Used on the port and starboard gangways, just below the flight deck, on s and through destroyers. Open single pedestal mount This was the first 5"/38cal type installed. It was put on the s in 1934 through to the (1937). Some of these mounts placed on ship's forecastles were partially enclosed to protect the crew against bow spray, but they were still considered an open mount. Since these mounts did not have Upper Handling Rooms, they could be installed on ships without extensive reconstruction. For that reason, they were frequently used on armed merchant ships. Farragut and Mahan had only open mounts. The Gridley class introduced the enclosed single gun house, but not all of its guns were enclosed. The Benham class replaced all pedestal mounts with open base ring mounts later on. The Fletcher class was the first to only have enclosed guns (except for the Porter and Somers destroyer leaders). There are several models of the 5"/38, differentiated by the word Mark (or its abbreviation MK) and a number. Variations to the basic design are called Modifications (or its abbreviation Mod). For instance, 5"/38 MK 21 is a single-barrel open pedestal mount widely used on amphibious ships, auxiliaries, and merchant ships. The 5"/38 MK 30 is a single enclosed base ring mount widely used on destroyer escorts. The 5"/38 MK 38 is a twin mount specifically designed for newer destroyers. Ammunition delivery Since this gun fires semi-fixed ammunition, each round is delivered to the gun in two piecesa projectile and a powder case. Base ring mounts The