Description

These guns were used on the only "Treaty" cruisers ever to serve in a South American Navy. Built by Odero-Terni at La-Foce and Livorno, Italy. These small cruisers were considered to be very successful by the Argentine Navy.

The guns were apparently a modified version of the 7.5"/45 (19 cm) Mark VI gun used on the Hawkins class cruisers. They seem to have been influenced by German designs, as the guns used a horizontally sliding breech mechanism and the propellant was split between a brass case and a silk bag, similar to German weapons. The breech mechanism was a semi-automatic design which closed when the cartridge case rim struck the ejectors.

Gun Characteristics

Designation 7.5"/52 (19 cm) O.T.
Ship Class Used On Veinticinco de Mayo class
Date Of Design 1927
Date In Service 1931
Gun Weight N/A
Gun Length oa N/A
Bore Length 389.0 in (9.880 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume N/A
Rate Of Fire 4.3 rounds per minute was achieved during testing 1
  • ^As these guns had a maximum loading angle of +12 degrees and both guns needed to be loaded together, I suspect that the practical rate of fire was about 3 rounds per minute.

Ammunition

Type Cartridge-Bag
Projectile Types and Weights SAPC - 198.4 lbs. (90.0 kg) 1a
Target - 198.4 lbs. (90.0 kg) 2a
Bursting Charge SAPC - 13.2 lbs. (6.0 kg)
Projectile Length N/A
Propellant Charge N/A
Muzzle Velocity 3,070 fps (936 mps)
Working Pressure N/A
Approximate Barrel Life N/A 3a
Ammunition stowage per gun 160 rounds
  • ^SAPC shells were officially designated as "SAP" but they had a thin AP cap and a very small ballistic cap, features that are more characteristic of a SAPC type.
  • ^The Target projectile was officially designated as "AP" but it did not have a burster and was used only for practice shots.
  • ^At such a high muzzle velocity, barrel life was probably quite short.

Range

Range of SAPC Shell with MV of 3,070 fps (936 mps)
Elevation Distance
45 degrees 29,860 yards (27,300 m)

Mount / Turret Data

Designation Twin Mounts 1b
   Veinticinco de Mayo (3): N/A
Weight N/A
Elevation -7 / +45 degrees
Elevation Rate N/A
Train +150 / -150 degrees
Train Rate N/A
Gun recoil N/A
Loading Angle -7 to +12 degrees
  • ^In appearance and in many details these mountings were similar in design to Italian 203 mm/53 Model 1927 twin mountings. Like those mountings, the two guns in these turrets were in a single slide.
  • Gun axes were 31.9 in (81 cm) apart.

Sources

"Naval Weapons of World War Two" by John Campbell
"Cruisers of World War Two" by M.J. Whitley
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"Catálogo de Granadas y Proyectiles" by Departamento Munición y Química de Guerra, 1958, p. 21
"Artillería" by División Náutica y Armas Navales, 1952, p. 28
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"Mystery of the South Seas. Argentine cruisers Almirante Brown and Veinticinco de Mayo"
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Special help by Alec Whalen and Iván Dubaniewicz

Page History

30 November 2007 - Benchmark
27 December 2021 - Converted to HTML 5 format, added SAPC details
10 December 2022 - Added details on gun construction, ammunition and mountings