The Ordnance QF 25-pounder, or more simply 25-pounder or 25-pdr, was the major British field gun and howitzer during the Second World War. Its calibre is 3.45-inch (87.6 mm). It was introduced into service just before the war started, combining both high-angle and direct-fire abilities, a relatively high rate of fire, and a reasonably lethal shell in a highly mobile piece. It remained the British Army's primary artillery field piece well into the 1960s, with smaller numbers serving in training units until the 1980s. Many Commonwealth of Nations countries used theirs in active or reserve service until about the 1970s and ammunition for the weapon is currently being produced by Pakistan Ordnance Factories. Initial production was slow, but by 1945, over 12,000 had been manufactured. The 25-pounder was probably the most outstanding field artillery piece used by British and Commonwealth forces in the Second World War, being durable, easy to operate and versatile. Design The design was the result of extended studies looking to replace the 18-pounder ( bore) field gun and the 4.5-inch howitzer (114.3 mm bore), which had been the main field artillery equipments during the First World War. The basic idea was to build one weapon with the high velocity of the 18-pounder and the variable propelling charges of the howitzer, firing a shell about halfway between the two in size, around of about . Development during the inter-war period was severely hampered by a lack of money and it was eventually decided to build a new design from existing 18-pounders by converting barrels but designing a new barrel and carriage for production when funds were available. The result was a weapon firing a shell weighing . It was mounted on late model 18-pounder carriages. One of these used a circular firing platform and this was adopted for the new guns. The firing platform was attached to the gun and when lowered the gun was pulled onto it. This platform transferred most of the recoil forces to the ground, instead of using the spade at the end of the trail, making the gun very stable when firing. It also provided a smooth flat surface for the carriage to rotate on using the road wheels, this enabled the gunners to traverse the carriage quickly in any direction. Unlike the 18-pounder, the 25-pounder used howitzer-type variable-charge ammunition. The 25-pounder was separate-loading; the shell was loaded and rammed, then the