Editing Iowa-class battleship (section)

====Secondary battery====

[[File:5-inch 38-caliber cropped.jpg|thumb|220px|alt=A grey turret with two gun barrels pointing forward. A black eagle, globe, and anchor insignia has been painted on the side of the turret.|A 5-inch gun mount emblazoned with the [[Eagle, Globe, and Anchor]] of the [[United States Marine Corps]] aboard the battleship {{USS|New Jersey|BB-62|2}}. In keeping with tradition, a 5-inch gun mount on each ''Iowa''-class battleship was manned by the ship's Marine Detachment.]]
The ''Iowa''s carried twenty [[5"/38 caliber gun|{{convert|5|in|0|adj=on}}/38 caliber]] Mark 12 guns in ten Mark 28 Mod 2 enclosed base ring mounts. Originally designed to be mounted upon destroyers built in the 1930s, these guns were so successful that they were added to many American ships during the Second World War, including every major [[Classification society|ship type]] and many smaller warships constructed between 1934 and 1945. They were considered to be "highly reliable, robust and accurate" by the Navy's Bureau of Ordnance.<ref name="NavWeaps 5/38">{{Harvard citation no brackets|NavWeaps.com|loc= [http://www.navweaps.com/Weapons/WNUS_5-38_mk12.php 5&quot;/38 Mark 12]}}</ref>

Each 5-inch/38 gun weighed almost {{convert|4000|lb|kg}} without the breech; the entire mount weighed {{convert|156295|lb|kg}}. It was {{convert|223.8|in|mm}} long overall, had a bore length of {{convert|190|in|mm}}, and a rifling length of {{convert|157.2|in|mm}}. The gun could fire shells at about {{cvt|2500|–|2600|ft/s}}; about 4,600 could be fired before the barrel needed to be replaced. Minimum and maximum elevations were −15 and 85&nbsp;degrees, respectively. The guns' elevation could be raised or lowered at about 15&nbsp;degrees per second. The mounts closest to the bow and stern could aim from −150 to 150&nbsp;degrees; the others were restricted to −80 to 80&nbsp;degrees. They could be turned at about 25&nbsp;degrees per second. The mounts were directed by four Mark 37 fire control systems primarily through remote power control (RPC).<ref name="NavWeaps 5/38" />

The 5-inch/38 gun functioned as a [[dual-purpose gun]] (DP); that is, it was able to fire at both surface and air targets with a reasonable degree of success. However, this did not mean that it possessed inferior anti-air abilities. As proven during 1941 gunnery tests conducted aboard {{USS|North Carolina|BB-55|2}} the gun could consistently shoot down aircraft flying at {{convert|12000|–|13000|ft|mi km}}, twice the effective range of the earlier single-purpose [[5"/25 caliber gun (United States)|5-inch/25 caliber]] AA gun.<ref name="NavWeaps 5/38" /> As Japanese airplanes became faster, the gun lost some of its effectiveness in the anti-aircraft role; however, toward the end of the war, its usefulness as an anti-aircraft weapon increased again because of an upgrade to the Mark&nbsp;37 Fire Control System, Mark 1A computer, and proximity-fused shells.{{sfn|Stillwell|1996|p=256}}{{sfn|Sumrall|1988|p=80}}

The 5-inch/38 gun would remain on the battleships for the ships' entire service life; however, the total number of guns and gun mounts was reduced from twenty guns in ten mounts to twelve guns in six mounts during the 1980s' modernization of the four ''Iowa''s. The removal of four of the gun mounts was required for the battleships to be outfitted with the armored box launchers needed to carry and fire Tomahawk missiles. At the time of the 1991 Persian [[Gulf War]], these guns had been largely relegated to littoral defense for the battleships. Since each battleship carried a small detachment of [[United States Marine Corps|Marines]] aboard, the Marines would man one of the 5-inch gun mounts.{{sfn|Wass|1984|p=27}}