Some surplus naval guns were allocated as coast defense drill guns, but few were actually used in that role.
The Mark I had an A tube which included the breech block, 4 hoops and a trunnion hoop over the breech end. This Mark was withdrawn from service after the similar 6" (15.2 cm) Mark II failed in the corvette HMS Cordelia in 1892. The other marks had an A tube and jacket which included the breech block and included the trunnions. They differed in the number and arrangement of hoops and tubes over the A tube between the jacket and muzzle. Mark II and Mark III were later chase hooped to the muzzle while the Mark IV and V were constructed with these in place. All were originally built with three-motion breech mechanisms. Altogether, 77 Mark I, 150 Mark II, 225 Mark III, 100 Mark IV and 82 Mark V were manufactured.
Twelve guns were later converted to drill guns by replacing the breech mechanism with a single motion Welin breech block. These were then redesignated as 5"/25 BLC Marks I/IV and Marks I/V. A breech ring was added and the trunnions repositioned. These changes also allowed an increase in muzzle velocity. One of these guns still survives in the Ordnance Museum at Priddy's Hard, Portsmouth.
These guns should not be confused with the later 5" (12.7 cm) field pieces also known as 60 pdrs nor should they be confused with the Australian coast defense guns which included EOC Pattern D 5"/31 (12.7 cm) guns.
The data that follows is specifically for Marks IV and V, but the other marks were similar.
5"/25 (12.7 cm) Mark III gun on Vavasseur
Mark I (VCPI) slide mounting
|Designation||5"/25 (12.7 cm) Marks I, II, III, IV and V|
|Ship Class Used On
|Sloops and cruisers of the 1880s|
|Date Of Design||About 1875|
|Date In Service||About 1878|
|Gun Weight||2.005 tons (2.04 mt) including breech mechanism|
|Gun Length oa||139.15 in (3.534 m)|
|Bore Length||125 in (3.175 m)|
|Chamber Volume||504 in3 (8.256 dm3)|
|Rate Of Fire||about 10 rounds per minute|
|Note: It had been intended to arm the Nile, Trafalgar, Scout and Fearless with these guns, but they were completed with the much better 4.7" (12 cm) QF guns.|
|Projectile Types and Weights||HE - 50 lbs. (22.7 kg)|
|4.45 lbs. (2.02 kg) Cord 7.5|
(see Note 1)
|1,750 fps (533 mps)|
|Approximate Barrel Life||N/A|
|Ammunition stowage per gun||100 rounds|
|Note: BLC Mark I/IV and I/V drill guns had their muzzle velocities increased to 1,905 fps (581 mps).|
|Elevation||With 50 lbs. (22.7 kg) HE Shell|
|Range @ 19.7 degrees||8,700 yards (9,510 m)|
|Range||Vertical Iron Plate|
|1,000 yards (9,140 m)||6.1 in (15.5 cm)|
|Note: Data from "British Battleships: 1860 - 1950."|
Iris (13 - as rearmed), Caroline (?), Pylades (?) and Garnet (?): VCPI, VBI and VBII
|Elevation||VCPI: -5(?) / +20 degrees
VBI: -5(?) / +15 degrees
VBII: -5(?) / +22 degrees
|Elevation Rate||Manually operated, only|
|Train||about -150 / +150 degrees|
|Train Rate||Manually operated, only|
|Note: These guns were used by many of the "masted cruisers" and RML armed ironclads of the late 1800s, but I lack details as to which ones and how many guns were carried.|
22 July 2006 - Benchmark
30 January 2009 - Added links, added "not to be confused with" information, added Mount / Turret data
07 December 2011 - Corrected typographical errors