others. The 25-pounder's main ammunition was the high-explosive (HE) streamlined shell with a 5/10 CRH ogive and boat tail. The explosive filling varied between 450-900g of TNT (854-1708 kilojoules of explosive energy). It was also provided with base ejection smoke (white and coloured), star shells, and chemical shells. Incendiary and coloured flare shells were developed but not introduced into service, and smoke shells were sometimes reloaded with propaganda leaflets or metal foil "window". The UK did not develop a WP smoke shell for the 25-pounder. For anti-tank use, the 25-pounder was also supplied with a limited amount of solid armour-piercing (AP) shot, later replaced with a more potent version with a ballistic cap (APBC). The AP shot was fired with maximum charge, charge No. 3, super, or super with Super increment depending on the ordnance mark, as muzzle velocity was critical in direct fire for penetration and a flat trajectory. A shaped charge anti-tank shell was under development in Canada, but the introduction of the three-inch (76.2 mm) calibre QF 17-pounder, an anti-tank gun, in 1944 ended its development. After the Second World War, the UK replaced AP shot with a HESH shell. Coloured marker shells (dye and PETN) were also developed but not introduced. The standard fuze was No 117 direct action (DA). No 119 (DA and graze) was also used. Combustion or mechanical time fuzes were used with base ejection shells and mechanical time with graze were used with HE. Proximity fuzes were used from the end of 1944 and subsequently replaced by CVT fuzes. British service The 25-pounder was the main field artillery weapon used by British Commonwealth and colonial infantry and armoured divisions of all types during the Second World War. It was also used by the RAF Regiment in North Africa. Throughout the war, each British-pattern infantry division was established with 72 25-pounders, in three field artillery regiments. Armoured divisions were eventually standardised with two field artillery regiments, one of which was self-propelled (see below). Before mid-1940, each regiment had two batteries of twelve guns; after that date, regiments changed to batteries of eight guns and added a third battery, a process that was not completed until early 1943. In the late 1950s, the British Army reverted to batteries of six guns. Field artillery regiments had two batteries of 25-pounders and one of 5.5 inch guns. The early 18- and 25-pounders had been towed in