Two types of 5" guns were used during World War II and a third was under development during the entire period of the war tut never reached service with the fleet. The 5"/38 caliber gun was used extensively on battleships, cruisers, destroyers, merchant vessels, and auxiliaries. The 5"/25 caliber gun, developed and produced during the war, became the main armament for submarines. Development of the 5"/54 rapid fire single and twin mounts was one of the major design problems and at the end of the war this gun was still in the design stage.
1. 5"/38 Guns
There were no basic changes in design of the 5"/38 guns during the period of World War II. Many minor changes were effected but emphasis was placed on production rather than development. At the beginning of the war the Bureau was in a sound position on the 5"/38 single mounts which were installed on most destroyers and some cruisers. Except for major developments in shields, the 5"/38 single mount on
these ships changed little after the beginning of the war. Numerous changes were made for installation of these guns on merchant ships and auxiliaries. Before the war the 5"/38 twin had been installed on the cruisers St. LOUIS and HELENA, but the real use started at the beginning of the war. The single purpose mounts on destroyers leaders were declared obsolete and replaced with double purpose twin mounts. During the war there was extensive installation of 5"/38 twins en battleships, although prior to the war they had been placed only on the WASHINGTON and NORTH CAROLINA. The 5"/38 guns were classified as follows:
(a) 5"/38 Base Ring Mounts
Single Mounts Mark 30 and Mods. This type of mount was designed for installation en destroyers and large naval auxiliary vessels. The same ring type of mount was completely enclosed in a mount shield and ammunition was supplied directly from the powder and projectile hoists mounted below the assembly.
Single Mounts Mark 37 and Mods. While the Mark 37 base ring mount was designed specifically for merchant vessel use, many of these mounts were assigned to naval auxiliary vessels and to special types
of vessels built by the Maritime Commission. The Mark 37 mount had no hoists or shield and the complete assembly, including the power drives and with the exception only of the gun and housing, was made by Northern Ordnance Incorporated.
(b) 5"/58 Pedestal Mounts Mark 24 Mod 2
This type of mount was installed on aircraft carriers, cruisers, destroyers, and auxiliaries. The mount had no shield or hoist and required less area for installation than the base ring type. It differed radically in manufacture from the base ring type in that the main components were casting instead of weldments. Shell fuzes were set by an auxiliary three-pot fuze setter mounted on the platform, whereas in the base ring mount fuzes were set in the projectile hoist itself.
(c) 5"/58 Twin Mounts. Mark 28 and nods. Mark 29 and Mods. Mark 52 and Mods, and Mark 38 and Mods
Development of this gun started in 1936 and installation was effected initially on new battleships and cruisers. This was an outstanding antiaircraft
mount and was superior to anything developed in other countries at that time.
2. 5"/25 Guns
With the failure of the 3"/50 caliber gun mount Mark 21, wet type, the Bureau of Ordnance designed a 4"/50 caliber wet type mount for submarines. This gun also proved ineffectual and in 1942 the Research and Development Division of the Bureau of Ordnance started design of new 5"/35 caliber wet type intended for installation principally on new submarines. The assembly was placed In service in March 1944 and provided a wet type mount which fired larger and heavier projectiles than former 3" and 4" wet mounts.
3. 5"/54 Guns
Development of the 5"/54 caliber single mount Mark 39 began in July 1942 and the assembly was placed in service in April 1945. Designed for installation on ships of the CV 41 Class, the gun fired a 60-pound projectile to a maximum altitude of 51,600 feet. The maximum range was 25,900 yards.
The design of the 5"/54 caliber twin mounts for destroyers was initiated in July 1944. The main purpose of the development was to obtain a smaller, more compact 5"/54 caliber twin mount for use on a destroyer of a new design.
b. History of 5"/38
1. Prewar Development of 5"/38; The Mark 37 Merchant Mount
(a) Inauguration of Program to Arm Merchant Vessels
The arming of merchant ships began in the fall of 1941 when provisions were made for arming all merchantmen in service. The approved armament plan for merchant vessels, designated "by the Chief of Naval Operations, took into consideration the availability of ordnance material, size of the ship, mission to be undertaken by and the possibility of attack by the enemy in various areas. Armament installed was obtained from the Navy Department by the Maritime Commission on loan basis. U. S. and foreign flag vessels alike were armed by the Maritime Commission with the exception of British flag vessels which were armed by the British themselves. In order to conserve 4"/50's the initial program called for 5"/50 or 5"/51 guns on vessels above 10,000 tons with 3"/50 DP guns forward. Vessels of 5,000 to 10,000 tons were to have one 4" gun aft and one 3" DP gun wherever practical from the structural standpoint. Early in 1942, it became evident that the existing supply of 4" and 5" single purpose guns available for arming
merchant vessels would be exhausted by about August of that year, and that any assembly selected to continue the supply of guns for arming merchant ships must be one which could be put into production by that time. The Bureau was, therefore, faced with the choice of putting the relatively simple but practically obsolete 4" and 5" single purpose guns Into production to provide for the Increased merchant ship program, or of designing a 5"/38 DP gun and mount combination sufficiently simplified to be suitable for this purpose.
(b) Selection of 5"/38. Extensively Modified for Merchant Arming Program.
In March 1942, a Board consisting of Commander E.E. Herrmann, senior member, Commanders F.F. Foster, A.D. Blackledge and A.S. Brumbaugh, was set up by the Chief of the Bureau to recommend a suitable gun and mount for merchant snips. The board held frequent meetings with representatives of CNO and the General Board. There was wide divergency of opinion and a marked tendency to favor a 3" or 4" single purpose gun in opposition to the opinion of the board established by the Bureau of Ordnance, which favored a 5"
gun. Finally, on April 6, 1942, the aboard met with representatives of the Bureau's Production Division and the design section of the Naval Gun Factory and
of the Northern Pump Company  and rejected the various existing calibers for the following reasons:
(a) 3"/50 was considered inadequate for defense against subs and possibly against raiders.
(b) 4"/50 was felt to "be barely adequate for the purpose for which it was required. There would be no advantage for conversion into dual purpose and production would be slow.
(c) The 5"/51 was Inadequate from the production standpoint and had the disadvantage of being a bag gun. In addition, there would be no advantage for conversion to double purpose.
At that time, the board recommended that the gun and mount selected to succeed the 4"/50 and 5"/51 in meeting merchant ship requirements be the existing 5"/38 assembly with base-ring type mount Mark 30, modified as follows:
(a) emission of ammunition hoist assembly.
(b) Hand-fuze setting wrench to be provided for presetting of fuzes.
(c) Omission of remote control features.
(d) Elevating and training arrangement consisting of hand drive through electrically powered hydraulic speed gears.
(e) Electrical power, where not available from ship's supply, to be provided by means of a gasoline-driven, quiet starting generating set.
(f) Omission of the sight then used on mounts; substitution of open sight with provision for addition of simple telescope.
(g) Provision for high pressure air (for the counter recoil system) by means of hand-operated pump and cylinder assembly of special design.
(h) Omission of shield.
(i) Inclusion of mounting pads for installation of indicators to facilitate possible future addition of fire control.
The Board determined that the principal components of the 5"/38 assembly Mark 30 were either actually in production or readily obtainable in quantities substantially in excess of requirements of existing naval ship programs. The aspects of installation, operation, and maintenance of the recommended assembly on board merchant snips were fully considered and the conclusion was reached that no insurmountable difficulties lay in that direction. On the other hand, the additional effort entailed in training men for maintenance of this assembly on merchant snips seemed well worthwhile in order to get a modern double purpose weapon which would constitute a sound investment not only for the present war but for possible future wars.
This program was approved by the Chief of Naval Operations on May 5, 1942, and the assembly became known as the Mark 37.
2. Status of 5"/38 Program at Beginning of War.
(a) 5"/38 Caliber Single Mounts (Base Ring Type) for DD's and Auxiliaries.
During 1939, two commercial manufacturers were
awarded contracts for the production of approximately thirty 5"/38 single double purpose mounts. The General Electric plant at Erie, Pennsylvania, was to produce a total quantity of ten, and the Goss Printing Press Company was awarded a contract for 20. At about the same time, the Naval Gun Factory undertook the production of approximately 20 mounts. As the Navy building program expanded, both private companies were awarded new contracts. Because of a limited maximum capacity, fire per month at General Electric and 12 per month at Goss, the Northern Pump Company at Minneapolis was brought into the program. In 1940 Northern was awarded a contract for approximately 700 of these mounts. Originally they were scheduled for only 100 but three increases brought the total to 700. In accordance with the terms of its contract, the northern Pump Company was required to produce this quantity over a period of three years. It not only fabricated these mounts, but manufactured a grand total of 955 single mounts within 16 months from the date of contract.
Extreme difficulty was experienced in delivering mounts in time to meet the requirements of the building program until November 1941, at which time production caught up with requirements.
Procurement of weldments and other associated equipment was satisfactory during this period with the exception of elevating and training electric-hydraulic power equipment and regulators. This material was critical because of plant expansion at the General Electric Company, and mounts were Installed without power until the fall of 1941.
From July 1, 1940, to November 30, 1941, 118 mounts and associated equipment were manufactured as compared with the 140 required for new construction.
(b) 5"/38 Gun and Single Pedestal Mount Assembly
Contracts for this program were completed in December 1940 with the Army Rock Island Arsenal and In November 1940 with the Naval Gun Factory. Under the contracts, the Rock Island Arsenal manufactured nine assemblies and four were completed at the Gun Factory. This was the exact number required for new
construction and there were no spares. Contracts were placed with the Herring-hall-Marvin Safe Company at Hamilton, Ohio, for 120 assemblies with delivery to start In March 1942, and with the new Naval Ordnance Plant which was to be established at Canton, Ohio, for 290 mounts with deliveries Beginning in June 1942.
(c) 5"/58 Twin Gun and Mount Assembly
This mount was originally designed and manufactured for CLs 49 and 50. Upon the authorization of CLs 51 to, 54, the Army was requested to assist the Naval Gun Factory in the manufacture of these mounts, with the result that 38 were produced by the Army at the Watertown Arsenal, Shortly after these vessels were authorized, directives were issued for the building of BBs 55 and 56 and the first vessels of the CL 55 class, all of which required 5" twin mounts as a secondary battery. With the exception of those assigned to the Watertown Arsenal, all of the mounts were produced by the Naval Gun Factory. Upon inspection by the Naval Gun Factory, those units being built by the Army, were found so poorly made according to Navy standards
that it was a major operation for the Gun Factory to modify and alter the mount in order to bring it even close to Navy specifications.
The 1940 expansion program required a total of 511 twin mounts. This did not include modernization of the antiaircraft facilities of battleships then in the fleet ad recommended by the King board. On account of the difficulties encountered by the Watertown Arsenal and the fact that the Gun Factory was overloaded with work, the Bureau of Ordnance sought commercial manufacturers to produce these mounts. At the time the Northern Pump Company was awarded a Contract for 5H single mounts, Mark 30, it was also given a contract for the production of about 75 twin mounts. Another contract was let to the Consolidated Steel Corporation for 68 twins. Various commercial firms were slated to manufacture the associated equipment and these contracts were not awarded in most cases until 1941. Slides, carriages, base ring weldments, roller paths, and training circles were made at Northern Pump Company and other commercial firms, while Vickers, Incorporated, Detroit, was making the powder and projectile hoist assemblies.
While satisfactory, production was, however, limited. From July 1, 1940 until November 30, 1941 66 twin assemblies were required for new construction, but only 63 were actually produced during this period.
3. Production Program During the War
(a) 5"/58 Merchant Mount Mark 57.
In the spring of 1942, contracts for 1,000 of the new Mark 37 merchant mounts were placed with Northern Ordnance Incorporated, formerly Northern Pump, which was already making 5" singles and twins for the Bureau. In view of its special relation to the program Northern Ordnance was given comparatively
free rein to initiate design of the modifications set up by a directive summary based on the Board's
report. However, it developed that Northern Ordnance Incorporated was going farther in the modification than was originally contemplated by the Bureau and Bureau officers accordingly discussed the proposed modifications In detail with Northern Ordnance at Its plant, and except for minor details, the design of the mount was frozen in June 1942. At that
time, it was noted that achievement of desired results in expediting the 5"/38 program probably depended on alleviation of the interference to which Northern Ordnance was being subjected by the Price Adjustment Board.
With the delay at Northern Ordnance, deliveries on the Mark 37 merchant assembly could not be made until the latter part of September 1942 and in the meantime it was decided to use the Mark 30 "hybrid"[sic] assembly and the Mark 30 Interim merchant type. They were used from July 1, 1942, until December of that year. These assemblies were similar to the Mark 37 except for the omission of train and elevation power drives. It was the understanding that power drives would be added to these mounts when they became available. Twenty-two Mark 30 hybrid" assemblies were distributed to merchant vessels during July and August. The first Mark 30 Interim merchant type mount was installed on a merchant ship in September 1942. The program was retarded by the slow delivery of mounts and gasoline-driven electric generators for power rammers, and by the lack of coordination in deliveries of base rings supplied by the Bureau of Ships. Delivery of Mark 30 Interim mounts was
critical since NOP Center Line and the Liquid Carbonic Company were unable to supply hand wheel brackets because their productive capacities were devoted to other essential programs. Between September and December of 1942, 30 of these Interim mounts were Installed on merchant vessels, 15 were shipped to merchant vessels then under construction, 14 were installed on AK's and AO's. During the period from December 1942 and June 1943, 131 Hark 30 hand-driven assemblies were manufactured and 150 of these were shipped to the Russian government after the Vice Chief of Naval Operations had approved the Russian requisition. The remainder were used for merchant vessel installations.
The first Mark 37 pilot model was expected to be delivered from Northern Ordnance by September 1942 but requirements could not be met and the assembly was not available until November. Two Mark 37 Mounts went through proof and upon inspection at the Naval Gun Factory were found to require certain changes in design. This resulted in a delayed delivery dated of the initial shipments. Requirements for
the Mark 37 assemblies were not met during November and December of 1942 because all available hand-wheel brackets at the Naval Gun Factory were used in assembling Mark 30 mounts. Additional hand-wheel brackets were not received because of the delay at the Liquid Carbonic Company.
Production began at a fairly rapid rate in January of 1943 but the Bureau was still unable to meet requirements for merchant vessels because it had been decided to use the new assemblies on DE's and naval auxiliaries and at some of the advance bases which had priority over merchant ship requirements. The Maintenance Division was directed to discontinue all shipments of Mark 37 assemblies to shipbuilding yards during January and February and distribution was not resumed until March. At this time delays arose in assembly and proof of slides, barrels, and housing which affected the meeting of merchant vessel requirements. During March 88 of the Mark 37 mounts were manufactured,and in April Northern Ordnance reached its goal of 100 a month. However, the proof and assembly of slides, guns, and housing remained behind schedule for several months.
Northern Ordnance continued to Increase its production until it reached 150 mounts per month In the fall of 1943 and was producing 200 by spring of 1944. By August of 1944, the program was cut back 500 assemblies and a reduction in delivery rate of 100 per month was ordered to begin in January 1945.
Up to July 1, 1945, a total of 3,298 assemblies had been manufactured at a cost of $227,562,000.
(b) 5"/58 Pedestal Mounts.
In December 1941, there were over 400 pedestal mounts en order for Installation of board carriers, heavy and light cruisers, and auxiliaries. At that time it was found that 145 of these mounts were in excess of requirements. It was decided, at first, to produce these 145 mounts with fire control equipment and to so arrange them that they could be driven by hand for possible installation at shore stations or on board merchant snips. With the development of the Mark 37 merchant mount, the order for pedestal mounts was reduced to 180 and all requirements in excess of that number were switched over to base ring mounts and manufactured at Naval Ordnance Plants.
In the spring of 1943, mounts delivered or on
order totaled 180, and requirements had then been reduced to 168, Including spares, indicating a surplus of 12; however, requirements for this program continued to decline so that "by the end of July 1945 only 161 pedestal assemblies had been produced.
The contract of the chief manufacturer of these mounts, the Herring-Hall-Marvin Safe Company at Hamilton, Ohio, called for 120 mounts. The remaining 60 were scheduled for manufacture at Naval Ordnance Plants. In 1942, difficulties arose over unsatisfactory production by Herring-Hall-Marvin and an investigation
disclosed incompetent management of this company. Deliveries were held up for several months; however, steps were taken to improve the organization of the company and hereafter production continued as scheduled.
Elevating and training power equipments for pedestal mounts were critical early in the program because of delays in expected initial deliveries from the Naval Ordnance Plant, Center Line, and difficulty in getting General Electric to increase deliveries of this type of equipment.
At the end of the war, a total of 161 pedestal assemblies load been delivered under this program. The total actual installation of these assemblies on combatant ships was 147 through August 15, 1945; 76 of which were on CVB's and CV's, CVL's or CVE's, 4 on cruisers, 58 on destroyers, and 9 on auxiliaries.
(c) 5"/58 Caliber Single Mounts Mark 50 (Base Ring Type).
Under the 1942 procurement program, a total of 1,489 base ring assemblies were to be procured for destroyers and auxiliaries. These assemblies were scheduled to be delivered by the-end of 1943. By that time 1, 349 of these assemblies had been produced.
These mounts were procured from the Naval Gun Factory and the following companies:
Northern Ordnance Incorporated, Minneapolis, Minn.
General Electric Company, Erie, Pennsylvania.
Goss Printing Press Company, Chicago, Illinois.
Northern Ordnance Incorporated was the major producer of this type equipment. From this program 85
mounts were diverted for installation on merchant vessels and 150 were assigned to Russia. At this time, the Bureau had on hand a large quantity of mounts, far exceeding the requirements. For this reason, and because the two other commercial manufacturers were producing at substantial rates, and the Navy operated plants were producing five to ten mounts per month, Northern Ordnance was assigned the task of designing and producing the 5"/38 merchant mount Mark 37. However, due to the rapid increase in completion of vessels by the shipbuilders throughout the country, and commitments to foreign governments, the stock pile of Mark 30's decreased at a rate which required a search for a new source of supply. Before the commitments to foreign governments and the rapid increase in the shipbuilding program, it had been estimated that the stock pile of these mounts would last a considerable time. The Army had reduced its program for the manufacture of 90 mm antiaircraft guns and the Bureau of Ordnance awarded contracts to the Fisher body Company and the Worthington Pump and Machinery Corporation, both of which had been engaged in the manufacture of mounts for the Army.
After settling some minor difficulties arising largely from the closer tolerances required by the Navy, and after making thorough studies during visits to the Gross Printing Press Company and the Danly Machine Specialties Company, Fisher Body Division was able to produce satisfactory mounts. On the other hand, Worthington, because of its knowledge of the Army program, apparently assumed that the 5" mount Mark 30 would be a relatively easy job to manufacture. This company's engineers visited various commercial and Navy plants, but these tours were more in the nature of sightseeing trips, and the Worthington production program presently ran into extreme difficulties. The Naval Gun Factory was obliged not only to reject the initial product but also to render assistance by sending personnel to the Worthington Plant. Other commercial manufacturers of products for this mount sent representatives to Worthington to impart their knowledge to that company.
In the fall of 1943, increased requirements called for approximately an additional 1800 mounts with deliveries beginning at the end of 1943 and continuing
throughout 1944, In this program were the replacements for the S35 mounts diverted from the 1942 program. About 750 of these mounts were scheduled for destroyer escort vessels; however, this quota was considerably decreased with the cancellation of 440 DE's, the conversion of 100 DE's to APB's, and the assignment of approximately 94 snips to foreign powers.
The above cutback took place at the time the Fisher Body Division was rapidly approaching Its maximum production of 50 mounts per month and Worthington had speeded its production to meet an estimated rate of 30 per month. Thus all commercial producers as well as Naval Ordnance Plants were required to stop production in June of 1944.
The commitments to foreign governments mentioned above involved principally the USSR. The Soviet Government, under protocol In December 1942, procured 150 5" single mounts Mark 30 with various modifications, including hand power in elevation and train. The modification, a major one, involved a considerable amount of work by the Naval Gun Factory. The Russian representatives would not inform the Bureau of Ordnance of their
intended use for these mounts other than that they were to be used in batteries of two and three mounts. It was necessary further to supply a generator set for each battery and approximately 300 meters of electric cable for each mount. The Philadelphia Navy Yard was directed to be the central assembly and storage facility for this project. Russian representatives requested delivery schedules which were impossible to meet. However, the availability of snipping space at times was such as to enable the Naval Gun Factory to ship mounts to Philadelphia In such quantities that very little available snipping space was lost. The entire project was completed, as far as the Bureau of Ordnance was concerned, In August 1943.
In the production of 5"/38 base ring assemblies Northern Ordnance Incorporated, Goss, Fisher Body, and the Naval Ordnance Plants performed outstandingly. There were many other manufacturers of component parts. The base ring, carriage, and slide weldments were manufactured by such companies as Danly, Babcock and Wilcox, and Welding engineers. Danly started production in 1940, with the Bureau of Ordnance providing
a specially designed plant and machine tool facilities. Danly experienced extreme difficulty with its initial production and considerable time elapsed before a satisfactory weldment was produced. However, once in production, and after developing the necessary technique and knowledge, the company turned out a good product.
Goes Printing Press Company manufactured nearly all of the 5" powder and projectile hoists required by the Navy for the 5" single mount. The manufacture of shields was confined to the Continental Gin Company and the Charles T. Brandt Company. Both of these manufacturers were able to far exceed their estimated maximum production rate and experienced little difficulty in producing a product which originally was a Considerable departure from their regular commercial product.
A total of 2,168 of the 5"/38 base ring assemblies were delivered up to November 1, 1945, at a total approximate cost of $216,800,000. The total actual installation of these assemblies on Navy ships as of August 15, 1945, was 1,683. Of this total 1,083 were Installed on destroyers, 210 on destroyer escorts, ten on battle-
ships, four on cruisers, 239 on auxiliaries, and 137 on other Navy ships.
(d) 5"/38 Twin Gun and Mount Assembly.
There were three types of 5"/38 twins - light medium, and heavy. The light types, Mark 38, were used on destroyers. The medium types, Mark 29 and Mark 32, were used on older battleships, heavy and light cruisers, and aircraft carriers, and the heavy type, Mark 28, was installed on newer battleships and cruisers. In December 1941, 71 of these assemblies had been produced which left a deficit of three assemblies.
When the 5"/38 caliber twin mount light type Mark 38 was released for production, the Naval Gun Factory indicated that if possible, Northern Ordnance Incorporated and the Consolidated Steel Corporation should make these mounts. Through the cooperation of two contractors, the Bureau of Ordnance was able to meet requirements for all 5" twin mounts without difficulty.
In 1942, the entire twin program was well underway, with 164 assemblies manufactured. This left a
slight deficit for modernization and spares. Production of mounts was held up by lack of cone gears from the Michigan Tool Company, which curtailed mount production at Northern Ordnance. However, with regard to the light type twin mounts, mount production was well ahead of power drives, this situation was relieved when Consolidated Steel began to assemble power drives and hand-wheel brackets to relieve Mare Island where assembly for modernization of mounts was taking place.
During 1943, 202 twin assemblies were produced. The main problem during this period seemed to be production of 5"/38 caliber twin mount sight hoods by Carrier Corporation. Deliveries of this item were very late due largely to defective castings supplied to the Carrier Corporation and purchased from the
United Steel Castings Division of Blaw-Knox Company.
Four hundred and seventy-five 5"/38 twin assemblies with mounts Mark 28, 32,and 38 were delivered In 1944, to a cumulative total of 912. Changes in armament and ship cancellations resulted In a cut-back of 129 of the Mark 52, leaving a total of 1,518 on order.
By August 1, 1945, actual deliveries of 5"/38 twin mounts totaled 1,257. With the Japanese surrender, this program was cut back in August 1945 and it was planned to terminate production at 1,347 assemblies.
The two sources of supply for the 5" twin mount power and projectile hoists were Busch-Sulzer Brothers and Willys-Overland Motors. While the initial rates were eight and six per month, respectively, under pressure of increasing requirements, tee former attained a maximum of 33 sets per month, and the latter IS sets per month. Here, two prices were reduced drastically as both manufacturers attained peak production and efficiency. Some manufacturing difficulties were experienced, principally because of substitutions of material. These were ironed out through cooperation between the companies and the Naval Gun Factory.
The 5"/38 twin mount shields were produced by the New York Navy Yard, the York Safe and Lock Company, the metropolitan body Company, and Copco Steel and Engineering company. The 5" twin mount weldments were produced principally by Danly Machine specialties Com-
pany. As with the 5"/38 base ring mount, this company had considerable difficulty at the start but later did a commendable Job. Other concerns Involved In the manufacture of twin mount weldments were Lakeside Bridge and Steel Company, Babcock and Wilcox, and Welding Engineers. The 5" twin mount roller paths were fabricated In part by Timken Holler Bearing Company, Kaydon engineering Company (which experienced extreme difficulty in producing an acceptable roller path), Midvale Company, and the Northern Ordnance Incorporated..
c. History of 5"/25
1. Development 
The 5"/25 wet mount was designed by the Bureau of Ordnance In 1942 and reached service In the Fleet In 1944. It was installed on new submarines and In limited quantities on submarines then operating with the fleet.
The gun had a range of approximately 14,000 yards at its maximum elevation of 40°, and was capable of being depressed to 10°. The complete assembly weighed approximately 14,000 lbs. The mount was entirely manual in operation, was hand-rammed and was equipped with a percussion firing mechanism. The component parts of the assembly were made either of corrosion-resistant materials or were plated so as to make them corrosion-resistant.
The gun and mount was designed to use a minimum installation space and to have a low silhouette.
The barrel Mark 17 had a corrosion-resistant nickel-cooper alloy under, chromium plated. No muzzle cover or breech cover was used so that there was a minimum of delay in opening fire. The breech mechanism was of the sliding wedge type which opened during the counter-recoil of the gun. A new type of operating
cam imparted constant acceleration to the operating shaft.
The mount was provided with a depression stop mechanism consisting of an external cam, which had a contour cut to suit the structure of the particular vessel upon which the mount was installed.
The sight mechanism was of counter-balanced modified yoke design. Special attention was paid to the comfort of the pointer and trainer in that the sights were so located as to be in the proper position with respect to the pointer's and trainer's eyes at all angles of elevation and depression.
The recoil system, of the hydraulic type, use a glycerine-water mixture as the hydraulic fluid. To give better stability to the housing in recoil and counter-recoil, two guide rails were attached to the housing and secured to a barrel of the gun by means of separable support. This arrangement provided for the even distribution of load throughout the length of the slide. The design recoil of the gun was 20".
8. Production Program
The first 5"/25 caliber wet mount was delivered in February 1944 for Installation aboard 33 441. At that time, It was estimated that approximately 441 assemblies would be required for new construction and for submarines already In service. During 1944, a total of 119 assemblies were delivered, 50 of which were turned over to the Maintenance Division, for installation on existing fleet submarines. Two cut-backs were initiated during the later part of 1944. The first was a cut from a total of 441 to 293. This was closely followed by another, reducing the total on order to 270. At the time of the Japanese surrender 241 assemblies had been completed and it was decided to complete the remaining assemblies to bring the total up to 270.
The contracts for the manufacture of these mounts were awarded to the Herring-Hall-Marvin Safe Company of Hamilton, Ohio, and the Harris-Seybold-Potter Manufacturing Company of Cleveland, Ohio. In addition, the Naval Ordnance Plants were requested to produce a small quantity of these mounts.
Many difficulties were experienced from the commercial sources and an unusual burden was placed on the Naval Gun Factory in that it was required to inspect practically every mount which was produced. Neither of the commercial manufacturers reached their possible maximum production rate because of production difficulties prior to VJ-Day.
d. History of 5"/54 Mounts
The 5"/54 caliber doulbe purpose single mount was designed for installation aboard the CVB 41 class. The mount was a base ring, enclosed, dual purpose type, mounting the 5"/54 gun Mark 16. The gun was capable of 85 degree elevation and 10 degree depresion and could be loaded nd fired at all angles within these limits. Power-driven powder and fuze setting projectile hoists supplied semifixed ammunition which was manually served to the shell case trays. A muzzel velocity of 2650 f/s gave maximum celing of 51,800 feet.
The 5"/54 gun Mark 16 was similiar in many respects to the %"/38 and had a sliding wedge breech mechanism, hydraulic dual cylinder recoil mechanism, and a hydro-pneumatic counter-recoil system.
The 5"/54 caliber single mount was trained and elevated in automatic, local control, or manual drive. Two Hand-wheill speeds were provided in local. The
train and elevation power drives were all electric, amplidyne type, and could move the mount at speeds up to approximately 15 degrees per second in elevation and 30 degrees per second in train. The 5"/54 single mount was the largest piece of naval ordnance to which this type of copntrol was applied, and it proviced unusually smooth, accurate, and quiet operation.
The design of the 5"/54 caliber twin mounts for destroyers was initiated in July 1944. The main objecive was to obtain a smaller 5"/54 caliber twin mount for destroyers of a new design. A design having the following general characteristics was accepted:(a) Gun Spacing 26.0"
(b) Streamlined shield (slightly smaller than 5"/38 twin).
(c) On mount gund director (Gunar Mark 1)
(d) 18 shots per gun per minute at all angles of elevation.
(e) Reduction of personnel required (10-12 per mount)
(f) Same size hole in main deck as 5'/38 twin mount.
(g) Automatic fuze setting with small variation in dead time.
(h) Reduction in size of handling room..
(i) Increased safety of ship (magzine all on one level, no exposed ammunition in upper part of ship, except that carried in hoists.
It was planned to use the new mouints on the CL 115 class of AA cruisers. The cruissers called for six center-line mouints in a stepped height arrangement which permitted maximum train angles for each mount. In order to install these mounts on cruisers, it was necessary to redesign only the ammunition hoists to suit the new deck heights. Schedules called for delivery to a pilot mount to the Naval Proving Ground, Dahlgren, early in 1947, and actual shipboard installation in 1949.
Outstanding characteristics of the mount were:
(a) No pointer, trainer, or sight setter was requied. Gunar Mark 1 uses one-man control with the optional use of a radar operator inside the mount.
(b) Ammunition for each gun, powder case and projective, was simultaneously but separately loaded into the hoist and handled automatically thereafter as a unit util fired.
(c) Empty casses were ejected under the gun barrel and forward of each mount.
2. Production Program
At the beginning of the 5"/54 production program in 1944, four vessels were scheduled to receive this equipment. The toal program was set at 91 units -- 18 for ech of the vessels, 18 spares and one pilot model. When CVB 44 ws cancelled production was cut back, and the spares stablilzed at 13 mounts, reducing the total program to 67 units.
The manufacture of this mount fell entirely on the Naval Gn factory with the exception of shields. A great deal of difficulty was experienced with this mount and the completed project was disappointing in that the ultimate rate of fire attained did not reach the estimated rate. In addion to this, liason between the Bureau of Ordnance and the Bureau of Ships with repsect to the mount was not as thorough as was needed. The Bureau of Ships in its design of teh CVB's did not provide for adequate hoisting of ammunition. Sponson space was insufficient for the proper elevating and traing-
ing of the mount so tht the antiaircraft qualities were limited. As a result of the inadequacy of the moun and its installation, the Research and Developomen Division of the Bureau of Ordnance began work on a new 5"/54 rapid fire single mount.
At the end of the war 37 assemblies had been deliverd and no cut-back was contemplated.
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