In 1895, the Brazilian Navy ordered four cruisers from the British firm of Armstrong, Mitchell and Co., Newcastle-on-Tyne. Brazil took delivery of only one of these, Almirante Barroso, while another was sold to Chile and renamed Ministro Zenteno. In March 1898 the remaining two were sold to the USA, which was interested in obtaining them in order to prevent their sale to Spain. These two warships were then rated as Protected Cruisers and renamed New Orleans (ex-Amazonas) and Albany (ex-Almirante Abreu) and were colloquially known in the USN as the "Elswick Cruisers."

These ships had a main armament of six 6"/50 (15.2 cm) guns built by Armstrong to their QF Pattern DD and a secondary battery of four 4.7"/50 (12 cm) guns. This armament was not well liked in the USN, as the guns used non-standard ammunition and spare parts. For that reason, the 4.7" (12 cm) guns were replaced in 1903 and the 6" (15.2 cm) guns followed in 1907. At that point these ships had a uniform battery of ten 5"/50 (12.7 cm) guns. In 1907 the removed British guns were emplaced in the Philippines on Grande Island and at the mouth of the harbor at Subic Bay.

Hooped construction from breech to muzzle.

The British 6"/50 Mark IX and Mark X were experimental coast defense guns with differing breech blocks. These were BL versions of the QF design used on the Brazilian/USN ships. Only one gun of each of these Marks was manufactured and these were designated as EOC Pattern DD¹ and DD², respectively. All of these guns were of built-up construction and had an actual bore length of 49.5 calibers.

The data that follows is for the 6"/50 (15.2 cm) Mark 5 (Armstrong) guns as used in USN service, but the guns on Brazilian and Chilean ships should be identical.

Designation	USA: 6"/50 (15.2 cm) Mark 5 (Armstrong) British: 6"/50 (15.2 cm) BL Marks IX and X
Ship Class Used On	USA: New Orleans Class Protected Cruisers (later PG-34 and PG-36, later still CL-22 and CL-23) Brazil: Almirante Barroso Chile: Ministro Zenteno
Date Of Design	about 1895
Date In Service	1898
Gun Weight	N/A
Gun Length oa	309.25 in (7.855 m)
Bore Length	300.0 in (7.620 m)
Rifling Length	N/A
Grooves	N/A
Lands	N/A
Twist	N/A
Chamber Volume	N/A
Rate Of Fire	About 6 rounds per minute

Type	Mark 5: Semi-fixed Marks IX and X: Bag
Projectile Types and Weights	CPC: 100 lbs. (45.3 kg) HE: 100 lbs. (45.3 kg)
Bursting Charge	N/A
Projectile Length	N/A
Propellant Charge	18.5 lbs (8.4 kg)
Muzzle Velocity	2,300 fps (701 mps)
Working Pressure	15.8 tons/in2 (2,500 kg/cm2)
Approximate Barrel Life	N/A
Ammunition stowage per gun	N/A

Range with 100 lbs. (45.4 kg)

Elevation	Range
30.8 degrees	17,500 yards (16,000 m)

Designation	Single Mounts    New Orleans (6): Armstrong center-pivot
Weight	N/A
Elevation	about -5 / +20 degrees (estimated from photographs)
Elevation Rate	Manual operation, only
Train	about +150 / -150 degrees
Train Rate	Manual operation, only
Gun recoil	N/A

"Warship Volume VII" article by John Campbell
"US Naval Weapons" and "U.S. Cruisers: An Illustrated Design History" both by Norman Friedman
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"United States Naval Guns: Their Marks and Modifications" Ordnance Pamphlet No. 127, December 1916, Revised January 1918
Letter published in "Warship International" No. 2, 1986 by Nelson H. Lawry
Gene Slover's Navy Pages

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