The 25 Pounder Field Gun

In May 1934 the General Staff issued a specification for a gun/howitzer to take the place of old weapons, the weapon was to...

• Have a weight in action of 30 cwt
• Fire a projectile weighting between 20 and 25lb
• Range at least 12,000 yards
• Rate of fire of 8 rounds per minute
• Self protection desirable but not to unduly affect the design
• Road performance of 25mph essential
• Mass production of the weapon was to use materials and plants readily available commercially.

The specification also included the convention of 18 Pounder guns for three reasons.

• The desire to obtain homogeneity for ammunition at the earliest date
• Large stocks of 18pdrs were available and later marks had a heavier carriage capable of taking a more powerful gun
• It had been decided to mechanize all field artillery and the additional carriage modifications were not serious

Trials of 18pdr, 22pdr and 25pdr projectiles were carried out and in April 1935 the 25pdr shell was decided upon, after this it was also decided the effective range of the equipment should be 15,000 yards. It was later pointed out that a weapon with this range would be incompatible with a carriage of 30 cwt due to the recoil stress involved, a shell capable of travelling this distance but with inferior lethal performance was proposed but rejected. A range of 13,500 yards was accepted by March 1936, development of the 25 pdr gun then proceeded.

Both box trail and split trail carriages were investigated in 1937 and the split trial type was chosen, pilot models were completed in 1938 and were found to exceed the specified weight considerably, it was then decided to revert to the box trail carriage, trails were arranged in October 1938 which were satisfactory, production drawings of the box trail pattern carriage were adapted and the necessary production capacity arranged.

The 18pdr was chosen for modification in December 1934, preliminary trials in the autumn of 1935 were successful, a battery of 18/25 pdr were ordered for intensive user trails. The modification of the gun consisted of lining it to 3.45" calibre and the carriage was pneumatised, a new buffer value and new sighting gear were also provided. The gun design was firm by the summer of 1936 and the carriage by the spring of 1938.

There were two marks of the Quick Firing 25pdr. The Mk I was the converted 18pdr, the Mk II new 25pdrs. The two Marks were separate weapons and the only common qualities were the ammunition and the trailer, the Mk I could not fire the super-charge and thus was limited to 11,500 yards.

25 Pounder gun details

 25 Pounder carriage details

Ammunition

The designs for High Explosive and Smoke shells were available in 1937, for anti tank use an armour piercing tip was designed to replace the fuze in HE. Design of armour piercing ammunition for the 25 pounder was not cleared until the winter of 1939/1940. Investigations into chemical shells began in 1937 and specifications were made available in 1939. To improve the performance of the 25 pounder AP round against face hardened armour a cap was provided, it was then realised that the cap would only help at velocities higher than the guns muzzle velocity so it was never used.

25 Pounder Projectiles

Production and conversion of 25 Pounder guns per year (UK only) * gun figures are not listed from June 1942 as they exceed carriage production

Production of 25 Pounder ammunition per year (Filled only, UK only)

Production of 18 Pounder ammunition per year (Filled only, UK only) *Data missing for several months, HE figures may include some smoke also

Sources -