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4.5 inch Howitzer

Gun

Mk 1 - Coventry Ordnance Works design
Mk 2 - Royal Gun Factory design with strengthened breech

Carriage

Mk 1 - Wooden wheels, steel tyres
Mk 1R - Wooden wheels, solid rubber tyres
Mk 1P - Steel disc wheels, pneumatic tyres
Mk 1PA - As Mk1P with improved sights & recoil system

Data

Wt gun & breech mech - 972 lb (Mk1), 1,021 (Mk2)
Wt in action - 3,010 lb (Mk1), 4,030 lb (Mk1P),
3,291 lb (Mk1PA)
Total length - 70 inches
Length of bore - 60.11 inches
Rifling - 32 grooves
Mk 1 - increasing RH 1/41.31 to 1/14.78
Mk 2 - uniform RH 1/20
Breech mech - Horizontal sliding block
Elevation - minus 5 to plus 45
Traverse - 3 L&R
Recoil system - Hydrospring variable
Recoil length - 115 to 43 inches

Approved for service on 19 March 1909 although first issued in 1908, it remained in service until declared obsolete on
13 September 1944. Due to be replaced by the 25 pdr, it was still in service in 1939 and served with the BEF in France & Belgium. It continued to serve with Home Forces until sufficient stocks of 25 pdr were available. It also served in the Far East, Eritrea and the Western Desert. It remained in use as a training weapon until ammo stocks ran out.

Performance

With 35 lb HE shell:
Muzzle velocity - 1,010 ft/sec
Max range - 7,000 yds

Ammunition

Shell HE Mk 12 to 16 - Amatol or TNT filled. Minor differences between marks
Shell Smoke Bursting Mk 3 to 11 - White phosphorus filled
Shell Smoke Base Ejection Mk 1 - Hexachloroethane/Zinc filled
Shell Star Mk 3 - Star unit & parachute with Fuze Time & Percussion No 221

Propelling Charge
5 part in 3.4 inch long brass case