40 (57 mm)] QF Marks I and II (original) (raw)

6-pdr Hotchkiss QF. Photograph copyrighted by John A. Roberts.

These guns were originally known as "6-pdr Hotchkiss guns" and were introduced in 1884 for use against torpedo boats. Used during World War I on the Arethusa and early "C" class cruisers and a few submarines as well as on Monitors M.15 through M.33.

Many were subsequently used as sub-caliber and saluting guns which meant that they were still available in 1939. That gave these guns a new lease on life, as many were hurriedly converted back to shooting guns for small ships such as MTBs, MLs and "Flower" class corvettes. Some weapons were also adapted for coastal defense.

The original Mark I gun had a barrel and short jacket with a locking hoop screwed to the front of the jacket. The Mark I* had a different recocking lever, but in 1890 all guns were altered to this standard and all guns were then redesignated as Mark I. During World War II, the converted ex-saluting guns were designated as Mark I*. Mark I** was apparently not in service, while Mark I*** were converted single tube guns left over from the First World War. The Mark II was an army gun converted to fit on naval mountings. All had vertical sliding breech blocks.

A total of 3,984 guns were on naval lists, but at least 2,344 of these had been stricken by 1939. Of those that remained, almost all were Mark I.

Designation	Hotchkiss 6-pdr / 8cwt QF Marks I and II
Ship Class Used On	Many
Date Of Design	1883
Date In Service	1884
Gun Weight	849 lbs. (385 kg)
Gun Length oa	97.63 in (2.480 m)
Bore Length	89.8 in (2.280 m)
Rifling Length	76.91 in (1.954 m)
Grooves	24
Lands	N/A
Twist	Uniform RH 1 in 30
Chamber Volume	46 in3 (0.754 dm3)
Rate Of Fire	20 rounds per minute

Type	Fixed
Weight of Complete Round	9.7 lbs. (4.4 kg)
Projectile Types and Weights	AP: 6.0 lbs. (2.72 kg) HE: 6.0 lbs. (2.72 kg)
Bursting Charge	N/A
Projectile Length	N/A
Propellant Charge	Prior to World War II: 0.243 lbs. (0.11 kg) CT World War II: 0.55 lbs. (0.249 kg) HSCT or 0.70 lbs. (0.318 kg) NF
Muzzle Velocity	1,765 fps (538 mps)
Working Pressure	N/A
Approximate Barrel Life	6,000 rounds
Ammunition stowage per gun 1	Monitors: 500 rounds Others: N/A

^Outfits for most ships included both AP and HE rounds.

Range with 6.0 lbs. (2.72 kg) HE

Elevation	Distance
45 degrees	8,700 yards (7,955 m)
AA Ceiling	10,000 feet (3,050 m)
Effective AA range	1,200 yards (1,100 m)

Range with 6.0 lbs. (2.72 kg) HE

Elevation	Distance
45 degrees	9,400 yards (8,600 m)

Designation	*Single Mounts Cruisers: Mark IC HA Flower Class corvettes: Non-recoil Small craft: Mark VI Coastal Mountings: Mark VI and VI Monitors: Mark IC HA and Mark IV HA
Weight	896 lbs. (406 kg) (? - 8cwt conversions)
Elevation	Mark IC HA: -8 / +60 degrees Non-recoil: -5 / +38 degrees Mark IV HA: -15 / +90 degrees Mark VI, VI* and VI**: -5 / +70 degrees
Elevation Rate	Manually operated, only
Train	360 degrees
Train Rate	Manually operated, only
Gun recoil	N/A

Some mountings were modified during World War I to allow HA fire.

Data from:

"Big Gun Monitors: The History of the Design, Construction and Operation of the Royal Navy's Monitors" by Ian Buxton
"Naval Weapons of World War Two" by John Campbell
"British Cruisers of World War Two" by Alan Raven and John Roberts
"Navy and Army Illustrated Annuals, Volume VI - 1898"

Special help by Dave Perkins

28 May 2008

Benchmark

15 December 2013

Added photograph of casing