View source for 203 mm/53 Italian naval gun

{{Infobox weapon
|name= ''Cannone da 203/53 Ansaldo''
| image=Regia Nave Fiume2.JPG
| image_size = 300
|caption=Forward guns on ''[[Italian cruiser Fiume|Fiume]]'', 1935
|origin= Italy
|type= [[Naval gun]]
<!-- Type selection -->
|is_ranged=YES
|is_bladed=
|is_explosive=
|is_artillery=YES
|is_vehicle=
|is_UK=
<!-- Service history -->
|service=1931–1944<ref name="Whitley">Whitley 1995 pp.149-156</ref>
|used_by= [[Regia Marina]]
|wars=[[Second World War]]
<!-- Production history -->
|designer=
|design_date=
|manufacturer=[[Gio. Ansaldo & C.]]
|production_date=
|number=
|unit_cost=
|variants=
<!-- General specifications -->
|weight=19.5 tonnes<ref name="Campbell">Campbell 1985 pp.326-327</ref>
|length=
|part_length=424 inches (10.8 meters)<ref name="Campbell"/>
|width=
|height=
|crew=
<!-- Ranged weapon specifications -->
|cartridge={{convert|125|kg|lb|sigfig=3}}<ref name="Campbell"/>
|caliber={{convert|8|in|mm|adj=on|sigfig=3}}<ref name="Campbell"/>
|action=
|rate=
|velocity=900 meters per second (2953 ft/sec)<ref name="Campbell"/>
|range=
|max_range= {{convert|31324|m|yd}}<ref name="Campbell"/>
|feed=
|sights=
<!-- Artillery specifications -->
|breech=
|recoil=
|carriage=
|elevation=
|traverse=
}}
The '''203&nbsp;mm/53 Ansaldo''' was the main battery gun of Italy's most modern [[Washington Naval Treaty]] [[heavy cruiser]]s. This treaty allowed ships of not more than 10,000 tons [[Displacement (ship)|standard displacement]], and with guns no larger than 8 inches (203&nbsp;mm), to be excluded from total tonnage limitations on a nation's [[capital ship]]s.
==Description==
These [[built-up gun]]s consisted of a liner, A tube, and full-length jacket with a hydraulically operated [[Welin breech block]].  Each heavy cruiser carried 8 guns mounted in 4 twin turrets with maximum elevation of 45°&nbsp;.  The 181 tonne turrets mounted both guns in a common cradle with centerlines only one meter apart.<ref name="Campbell"/>  This mounting practice was chosen to reduce the weight, but mutual interference increased dispersion during salvo fire.<ref name="Whitley"/>  Each gun could fire approximately four rounds per minute.  The Model 1929 guns aboard ''Bolzano'' were mounted on a turret with thinner armour than the previous models, to further reduce its weight.<ref name="Campbell"/>
==Ammunition==
===Propellant Charges===
Initially, the Armor-Piercing and High-Explosive shells used two different propellant charges, both initially using ‘C’ (smokeless) Powder, in two bags (later, as they became available this was replaced with NAC and FC4-type powders). APC rounds used a 50.8&nbsp;kg charge for a working pressure of 3,360&nbsp;kg/cm<sup>2</sup> and a muzzle velocity of 960 meters per second, while HE rounds used a 41.8&nbsp;kg charge for a working pressure of 3,250&nbsp;kg/cm<sup>2</sup> and a muzzle velocity of 940 meters per second. Due to the excessive dispersion experience by the guns, it was decided to lower the muzzle velocity of the APC rounds by utilizing the same (weaker) charge as the HE shells – 41.8&nbsp;kg. This reduced working pressure to the same as the HE shells, and muzzle velocity of the APC fell to 900 meters per second, with the added benefit of simplifying ammunition supply (since the same charges were thus used for all ammunition types). This effort, however, did not substantially affect dispersion, since the root of the problem was the mounting of the guns in a common cradle, rather than the high velocity of the weapons.<ref name=":0">Campbell, p. 326</ref>
Initially these guns, like most large-caliber guns of the Regia Marina, lacked flashless powder (''vampa ridotta''), which was necessary for night combat. The first tests of flashless powder on the 203mm did not occur until early 1941, aboard the cruiser ''[[Italian cruiser Fiume|Fiume]].''
===Shells===
'''AP:''' The Armor-Piercing shells used by the 203mm/53 was known as ‘Granata Perforante” (“Piercing Shells”). Their mass (125.3&nbsp;kg) was average for their caliber), with a bursting charge that was lesser than average for Granata Perforante shells (3.57 to 5.57%), but greater than the other type of armor-piercing shot (Palla/Proiettile Perforante, 1.15 to 1.69%), at 2.51%, or 3.157&nbsp;kg TNT. Shells had a steel sheath-type armor piercing cap, while the ballistic cap was aluminum (although at one point they were of a magnesium alloy) and were 87.4&nbsp;cm in length, or 4.17 calibers long.<ref name=":1">Campbell, p. 318</ref>
'''HE:''' High-Explosive shells (Granata Dirompente), which weighed 110.57&nbsp;kg and had a 7.5&nbsp;kg TNT (6.8%) bursting charge. Although these shells were typically nose-fused, some may have had base-fuses.<ref name=":1" />
{| class="wikitable"
|+
!Shell Type
!Mass
!Bursting Charge
!Fuse Type
!Muzzle Velocity
!Range
|-
|AP
|{{Convert|125.3|kg|lb|abbr=on}}
|{{Convert|3.157|kg|lb|abbr=on}}
|Delayed-Action Base Fuse
|{{Convert|900|m/s|ft/s|abbr=on}}
|{{Convert|31324|m|yd|abbr=on}} @ 45º
|-
|HE
|{{Convert|110.57|kg|lb|abbr=on}}
|{{Convert|7.5|kg|lb|abbr=on}}
|Instantaneous Nose Fuse
|{{Convert|940|m/s|ft/s|abbr=on}}
|{{Convert|30547|m|yd|abbr=on}}* @ 45º
|}
<nowiki>*</nowiki>Range corresponds to a listed velocity of {{Convert|930|m/s|ft/s|abbr=on}}
As previously mentioned, the original velocity was {{Convert|960|m/s|ft/s|abbr=on}}. Maximum range at +45º elevation was {{Convert|34208|m|yd|abbr=on}} at a velocity of {{Convert|950|m/s|ft/s|abbr=on}}.
==Performance==
These guns were mounted in twin turrets on the four cruisers of the [[Zara-class cruiser|''Zara''-class]], and the one-off ''[[Italian cruiser Bolzano|Bolzano]]'', the turrets being designated Modello 1927 and Modello 1929 respectively. The M1929 was designed to be lighter, which was primarily achieved through thinner faceplate armor (reduced from 150mm to 100mm).<ref>{{Cite book|title=Gli incrociatori italiani, 1861-1964|first=Giorgio|last=Giorgerini|date=1964|pages=542|oclc=164884426}}</ref> The cruisers mounted four turrets, all on the centerline. The guns were not individual sleeved, instead being mounted in a common cradle spaced one meter apart, and had a recoil distance of 55 centimeters. The turrets were electrically powered. Depression was to a minimum of -5º and elevation to a maximum of +45º, and could be achieved at a rate of 5º/second. Traverse, ±150º in either direction from the centerline, was achieved at a rate of 6º/second. The more heavily armored M1927 turrets of the ''Zara''-class weighed 181 metric tonnes, while the weight of the M1929 is not known, although it was lighter.<ref name=":0" />
Loading could be conducted at any elevation, which was of considerable advantage to maintaining rate of fire. This was achieved via the hydraulic rammers being attached to the gun cradles, enabling their operation at any point in elevation. The rate of fire per gun was one round every 16 seconds (3.8 rounds per minute).
Performance was high – only the German [[20.3 cm SK C/34 naval gun|20.3cm SK C/34]] had a longer ballistic range after the Italian guns reduced their APC velocity, although much of this range was not practically usable (although in theory both guns were capable of firing past 30&nbsp;km, the longest-ranged 203mm hits of the war would only be scored at 22&nbsp;km, and the longest-ranged salvoes were fired at around 24&nbsp;km).<ref>Campbell, p. 235</ref> Penetration was high for the caliber, but unlike many other high-penetration 203mm guns the bursting charge was still quite large for the caliber (only surpassed among the caliber by the British SAPC shells), giving the guns some of the best hitting-power of their caliber.  The ability to sustain loading operations at any elevation meant that rate of fire at long ranges was not hampered by loading procedures, as in many other 203mm guns.
However, these guns had two significant drawbacks. The first was a low liner life, due to the high working pressures and muzzle velocities, but this was largely countered by the fact the guns had loose liners, which could be changed out on board the cruisers. This comparatively easy (versus other methods) process of replacement meant that replacement of the liner could be carried out relatively quickly, before velocity loss became excessive (the fire control system being able to tolerate losses of up to 50 meters per second).<ref>{{Cite book|title=La Condotta del tiro navale da bordo nella Regia Marina 1900-1945|last=Santarini|first=Marco|publisher=Ufficio Storica della Marina Militare|year=2017|isbn=9788899642105|location=Roma|pages=159}}</ref> The second major drawback, and the more consequential of the two, was the fact the guns were mounted in a common cradle. At the time the ships were built, it was a fairly common method of weight-saving for main battery turrets (most widely utilized by the [[United States Navy]] in [[14"/50 caliber gun|14”]] and [[8"/55 caliber gun|8”]] triple turrets), but due to the proximity of the guns to each other, it would result in interference of the shells in flight immediately after they left the barrels, causing excessive dispersion at long range.<ref>Bagnasco, p. 24-5</ref>
The two earlier [[Trento-class cruiser|''Trento''-class cruisers]] mounted in the same configuration the earlier [[203 mm /50 Model 1924|203mm/50 Model 1924 gun]]. It differed from the later guns by having a fixed liner, a fixed loading angle of +15° and a single ammunition elevator, which reduced the rate of fire; dispersion was even more prominent than in the later guns.<ref>Bagnasco, p. 24</ref>
==See also==
===Weapons of comparable role, performance and era===
*[[BL 8 inch Mk VIII naval gun]] British equivalent
*[[203mm/50 Modèle 1924 gun]] French equivalent
*[[20.3 cm SK C/34 Naval gun]] German equivalent
*[[20 cm/50 3rd Year Type naval gun]] Japanese equivalent
*[[8"/55 caliber gun]] US equivalent
==Notes==
{{reflist}}
==References==
* Bagnasco, Erminio. ''Le armi delle navi italiane nella Seconda Guerra Mondiale'' Parma, Albertelli, 1978 (ed. 2007) {{ISBN|88-87372-40-3}}
* {{cite book| title=Naval Weapons of World War Two |author=Campbell, John |publisher=Naval Institute Press |year=1985 |isbn=0-87021-459-4}}
* {{cite book| title=Cruisers of World War Two |author=Whitley, M.J. |publisher=Brockhampton Press |year=1995 |isbn=1-86019-874-0}}
==External links==
{{Commons category}}
* Tony DiGiulian, [http://www.navweaps.com/Weapons/WNIT_8-53_m1927.htm Italy 203 mm/53 (8") Models 1927 and 1929]
{{DEFAULTSORT:203 mm 53 Italian naval gun}}
[[Category:203 mm artillery]]
[[Category:World War II naval weapons]]
[[Category:World War II artillery of Italy]]
[[Category:Naval guns of Italy]]
[[Category:Military equipment introduced in the 1930s]]