page_title: QF 4.5-inch Mk I – V naval gun
section_title: Land service
hierarchical_section_title: QF 4.5-inch Mk I – V naval gun / Land service
caption_attribution_description: English: 4.5-inch anti-aircraft gun of 207th Anti-Aircraft Battery, Royal Artillery, at Iwade near Sittingbourne in Kent.
context_page_description: The QF 4.5 inch gun has been the standard medium-calibre naval gun used by the Royal Navy as a medium-range weapon capable of use against surface, aircraft and shore bombardment targets since 1938. 5 inch Mark 8 naval gun.
  Like all British nominally 4.5 inch naval guns, the QF Mk I has an actual calibre of 4.45 inches.
context_section_description: QF Mark II was a single gun mounting (Mounting Mk 1) anti-aircraft gun in static sites.  The pedestal mount was bolted to concrete in an unarmoured turret, a travelling platform was available to transport the gun and mounting between positions. The first unit became operational in February 1939. These 16.5 ton anti-aircraft mountings had a maximum elevation angle of 80 degrees.  However, most mountings were Mark 1A with an elevation range of -9.5 to 80 degrees. This enabled the gun to be dual role (anti-aircraft and coastal defence) in coastal areas. Armour piercing rounds were provided for anti-ship engagements.
  The guns were fitted with Magslip electrical data transfer from Predictors AA Nos 3, 5 and 10 and were probably used initially with GL radars and UB 10 18 feet base optical height and range finders.  AA control radars evolved rapidly. The gun was laid and fuzes set by pointer matching, it is unclear the extent to which advances in 3.7-inch fire control were applied to 4.5-inch.  During the war Machine Fuze Setter No 10 was added, This improved the rate of fire from 8 to 10 rounds per minute and raised the effective ceiling to 34,500 feet.
  Gun positions were usually in the vicinity of naval bases where they could use the naval ammunition supply. However, initially the standard fuze was an igniferous design, No 199 with a maximum running time of 30 seconds that limited performance.  Subsequently, No 209 a mechanical time fuze was introduced.  It appears that VT fuzes were not issued.
  Guns were usually deployed in troops of 4 as part of a two-troop battery, although sections of two guns occupied some positions.  Deployment included:
  UK (Royal Artillery) June 1940:
  1st AA Division - 48
  2nd AA Division - 40
  3rd AA Division - 64
  4th AA Division - 52
  5th AA Division - 24
  6th AA Division - 52
  7th AA Division - 64
  (the AA divisions included 3-inch and 3.7-inch regiments in addition to 4.5-inch)
  Far East January 1942:
  Singapore - 4 (Hong Kong & Singapore Artillery)
  Mediterranean June 1943:
  Malta - 10
  Middle East January 1943:
  Aden - 2 (Hong Kong & Singapore Artillery)
  Port Said - 2 (Royal Malta Artillery)
  West Africa Dec 1941:
  Takoradi - 6
  India Dec 1941:
  Bombay - 6
  Colonel Probert of the Armaments Research Department developed rifling with tapered groove depth, and with the last few inches of the barrel being smoothbore. This was used with a 4.5 barrel lined down to 3.7 inches, but retaining the large chamber, allowing a large propelling charge to be employed. Ordnance, QF 3.7 inch Mk 6, only on a static mounting, entered service in 1943 and continued in service until 1959.  It had an effective ceiling of 45,000 feet.
  The high performance of QF 3.7 inch Mk 6 and QF 5.25 inch meant that QF 4.5 inch was not retained in land service after World War II.
caption: 4.5 inch anti-aircraft gun and crew near Sittingbourne, Kent, January 1941
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