Question: What branch of service were the Nevada-class battleship and the 16"/45 caliber gun used by?
Context: The Mark 42 5"/54 caliber gun (127mm) is a naval gun (naval artillery) mount used by the United States Navy and other countries.  It consisted of the Mark 18 gun and Mark 42 gun mount.  United States naval gun terminology indicates the gun fires a projectile 5 in in diameter, and the barrel is 54 calibers long (barrel length is 5" × 54 = 270" or 6.9 meters.)  In the 1950s a gun with more range and a faster rate of fire than the 5"/38 caliber gun used in World War II was needed, therefore, the gun was created concurrently with the 3"/70 Mark 26 gun for different usages.  The 5"/54 Mk 42 is an automatic, dual-purpose (air / surface target) gun mount.  It is usually controlled remotely from the Mk 68 Gun Fire Control System, or locally from the mount at the One Man Control (OMC) station. The 14"/50 caliber gun was a naval gun mounted on "New Mexico" and "Tennessee"-class battleship s.  These ships also featured the first "three-gun" turrets, meaning that each gun in each turret could be "individually sleeved" to elevate separately (however, they could be linked so they would elevate as a unit, similar to the triple turrets on other Navy ships).  The 14"/50 caliber guns were designated as Mark 4 and 6, with later versions known as Mark 7, 11, and B.  These guns were more powerful than the main gun mounted on the previous three classes of US battleships (the "New York" , "Nevada" and "Pennsylvania" class es), the 14"/45 caliber gun. <ref name="14/50"> </ref> The 14"/45 caliber gun, (spoken "fourteen-inch-forty-five-caliber"), whose variations were known initially as the Mark 1, 2, 3, and 5, and later as the Mark 8, 9, 10, and 12, were the first 14 in guns to be employed with the United States Navy, and were for over a year the most powerful naval ordnance afloat.  They were installed aboard the United States Navy's "New York"-class , "Nevada"-class , and "Pennsylvania"-class battleship s as the primary armament for each battleship in the class.  The gun also saw service in the British Royal Navy, where it was designated the BL 14 inch gun Mk II. The 16"/45 caliber gun (spoken "sixteen-inch-forty-five-caliber") was used for the primary batteries of the last class of Standard-type battleships for the United States Navy, the "Colorado"-class .  These guns promised twice the muzzle energy over the Mark 7 12-inch/50 caliber guns of the "Wyoming"-class battleship and a 50% increase over the 14-inch/45 caliber guns of the "New York"-class , "Nevada"-class , and "Pennsylvania"-class battleship s. The 16"/45 caliber Mark 6 gun is a naval gun designed in 1936 by the United States Navy for their Treaty battleships.  It was first introduced in 1941 aboard their "North Carolina"-class battleship s, replacing the originally intended 14"/50 caliber Mark B guns and was also used for the follow-up "South Dakota" class.  These battleships carried nine guns in three three-gun turrets.  The gun was an improvement to the 16"/45 caliber guns used aboard the "Colorado" class , and the predecessor to the 16"/50 caliber Mark 7 gun used aboard the "Iowa" class . Type 3 120 mm 45 caliber naval gun was a Japanese naval gun and coast defense gun used on destroyers, submarines and torpedo boats of the Imperial Japanese Navy during World War I and World War II.  The proper title of the gun under the Japanese naval artillery naming system is 12 cm/45 3rd Year Type naval gun.  Other guns using this naming system are the 41 cm/45 3rd Year Type naval gun, 20 cm/50 3rd Year Type naval gun, 15.5 cm/60 3rd Year Type naval gun and the 12.7 cm/50 Type 3 naval gun. 6 inch 35 caliber naval gun 1877 was a 152 mm naval gun used by Russian Empire.  The gun was used from 1887 as battleship secondary armament and cruiser armament.  The gun was mostly replaced by newer 6 inch 45 caliber Canet gun 1892 by Russo-Japanese War, but was still used on some ships.  During the First World War fourteen guns were used as a coastal guns on Gulf of Finland in the Peter the Great's Naval Fortress and were taken over by Finland after Finland's Declaration of Independence in 1917.  The guns were used by Finland in the Second World War.  Russian model year 1877 refers to rifling system, not gun adoption . The 7"/44 caliber gun Mark 1 (spoken "seven-inch-forty-four--caliber") and 7"/45 caliber gun Mark 2 (spoken "seven-inch-forty-five--caliber") were used for the secondary batteries of the United States Navy's last generation of pre-dreadnought battleships, the "Connecticut"-class and "Mississippi"-class .  The 7 in caliber was considered, at the time, to be the largest caliber weapon sutiable as a rapid-fire secondary gun because its shells were the heaviest that one man could handle alone. The 10"/31 caliber gun Mark 1 Mod 1 (spoken "ten-inch-thirty-one--caliber") and the 10"/35 caliber gun Mark 1 Mod 2 were both used for the primary batteries of the United States Navy's "Amphitrite"-class monitor "Miantonomoh" .  The 10"/30 caliber gun Mark 2 was used as main armament on the remaining Amphitrite-class monitors, the monitor "Monterey" , and the armored cruiser "Maine" . The two "Nevada"-class battleship s were the first Standard-type battleships produced by the U.S. Navy, and also the first to use triple main turrets.  "Nevada" (BB-36) and "Oklahoma" (BB-37) were both ordered in March 1911.  In armament, armor, and propulsion the "Nevada" class represented a considerable evolution in battleship design and, in being designed specifically to fight at extreme gunnery ranges, was actually well ahead of its time.  They would be followed by the "Pennsylvania"-class battleship s.
Answer: Navy