4.5 inch Howitzer

4.5 inch How

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 British Expeditionary Force 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.

Gun

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

Carriage

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

Crew

No.1 Detachment Commander
No.2 Breech Operator – gun rule
No.3 Layer – fires gun
No.4 Loader
No.5 Ammunition
No.6 Ammunition

Data

Weight of gun & breech mechanism 972 lbs (Mark 1), 1,021 lbs (Mark 2)
Weight in action 3,010 lbs (Mark 1), 4,030 lbs (Mark 1P), 3,291 lbs (Mark 1PA)
Total length 70 inches
Length of bore 60.11 inches
Rifling 32 grooves
Mark 1 – increasing right hand 1/41.31 to 1/14.78 at 5.87 inches from muzzle, thereafter uniform
Mark 2 – uniform right hand 1/20
Breech mechanism Horizontal sliding block
Elevation -5º to +45º
Traverse 3º left & right
Recoil system Hydrospring variable
Recoil length 115 to 43 inches

Performance

With 35 lb High Explosive shell:  
Muzzle velocity 1,010 feet/second
Maximum range 7,000 yards

Ammunition

Shell High Explosive Mark 12 to 16 Amatol or TNT filled. Minor differences between Marks
Shell Smoke Bursting Mark 3 to 11 White phosphorus filled
Shell Smoke Base Ejection Mark 1 Hexachloroethane/Zinc filled
Shell Star Mark 3 Star unit & parachute with Fuze Time & Percussion No 221
 
Propelling Charge
5 part in 3.4 inch long brass case