Ordnance BL 6-inch gun Mk XXII
Gun turrets on HMS Rodney, 1940
Type	Naval gun
Place of origin	United Kingdom
Service history
In service	1927 – 1947
Used by	United Kingdom
Wars	World War II
Production history
Designed	1921
No. built	40
Variants	Mark XXII*
Specifications
Mass	19,824 lbs. (8,992 kg)
Barrel length	300 inches (7.620 m) bore (50 calibres)

Shell	1927 : 100 pounds (45 kg) 1942 : 112 pounds (51 kg)^[1]
Calibre	6-inch (152.4 mm)
Breech	364 lbs. (165.1 kg) Welin interrupted screw
Recoil	16.5 in (42 cm)
Elevation	-5 / +60 degrees
Traverse	+100 / -100 degrees
Rate of fire	5 rpm
Muzzle velocity	898 metres per second (2,950 ft/s)^[1]

The BL 6-inch Mk XXII gun^{[note 1]} was a British high-velocity 6-inch 50-calibre wire-wound naval guns deployed on the Nelson-class battleships from the 1920s to 1945.

Background

They were originally designed as secondary armament for the proposed G3 class battlecruisers. When the G3 class were cancelled after the Washington Naval Treaty the guns and mountings were later used as secondary armament on the two Nelson-class battleships, serving throughout World War II. The Nelsons were the first British battleships since the Lord Nelson class of 1904 to carry their secondary armament in turrets rather than in broadside casemates. The Mk VIII gun mountings could elevate from +60 degrees to -5 degrees, while the telescopic power rammers for the gun loaded at a +5-degree fixed angle.^[2] Although classified as a dual-purpose gun and capable of high-angle fire, their training and elevation speeds were too slow for the anti-aircraft role and their main use was against surface targets.

Ammunition

The gun originally fired a 100-pound (45 kg) shell, which had been the standard shell weight for six-inch guns since 1880. From 1942 the gun fired the same 112-pound (51 kg) shell introduced for the later Mk XXIII gun.^[3] Figures in the table below are for the 100lb shell.

Shell trajectory

Range^[2]	Elevation	Time of flight	Descent	Impact velocity
5000 yd (4.6 km)	2° 5.2′	6.20 sec	2° 48′	2029 ft/s (618 m/s)
10000 yd (9.1 km)	5° 37.2′	15.22 sec	9° 13′	1390 ft/s (424 m/s)
15000 yd (14 km)	12° 5.4′	28.55 sec	23° 2′	1094 ft/s (333 m/s)
20000 yd (18 km)	22° 54′	46.14 sec	39° 46′	1056 ft/s (322 m/s)
25000 yd (22.86 km)	42° 37′	74.92 sec	59° 0′	1148 ft/s (350 m/s)

Notes

References

Bibliography

External links

British Commonwealth naval weapons of the Second World War

British Commonwealth naval weapons of the Second World War
Monitor guns	BL 15-inch
Capital ship main armament	BL 14-inch BL 15-inch BL 16-inch
Heavy cruiser main armament	BL 7.5-inch Mk VI BL 8-inch Mk VIII
Secondary armament and light cruiser main armament	QF 4-inch Mk V QF 4.5-inch QF 5.25-inch BL 5.5-inch BL 6-inch Mk XII BL 6-inch Mk XXII BL 6-inch Mk XXIII
Minesweeper, Sloop, Corvette, Frigate and Destroyer armament	QF 6-pounder 10 cwt QF 12-pounder 12 cwt Mk V QF 4-inch Mk IV BL 4-inch Mk IX QF 4-inch Mk XVI QF 4-inch Mk XIX QF 4.5-inch BL 4.7-inch Mk II QF 4.7-inch Mk IX & XII QF 4.7-inch Mk XI
Submarine guns	QF 12-pounder 12 cwt Mk V QF 3-inch 20 cwt QF 4-inch Mk XII & XXII
Anti-aircraft weapons	Unrotated projectile Holman Projector 20 mm Oerlikon QF 2-pounder "pom-pom" Mk VIII 40 mm Bofors QF 3-inch 20 cwt QF 4-inch Mk V QF 4-inch Mk XVI QF 4.5-inch QF 4.7-inch Mk VIII
Light weapons	.303 Lewis machine gun .50 Vickers Mk III machine gun QF 3-pounder Vickers
Torpedoes	21-inch Mk VII 21-inch Mk VIII 21-inch Mk X 21-inch Mk XI 24.5-inch Mk I
Anti-submarine weapons	Thornycroft depth charge thrower Hedgehog Squid
Small craft armament	Molins 6-pounder Vickers K machine gun 18-inch torpedo
Foreign-sourced weapons	20 mm Oerlikon 40 mm Bofors 3-inch 23 caliber gun (US) 3-inch 50 caliber gun (US) 4-inch 50 caliber Mark 9 gun (US) 5-inch 51 caliber Mark 8 gun (US) Y-gun depth charge projector (US) Mark 8 torpedo (US)