FV433, 105mm, Field Artillery, Self-Propelled "Abbot" is the self-propelled artillery, or more specifically self-propelled gun (SPG), variant of the British Army FV430 series of armoured fighting vehicles (AFVs), using much of the chassis of the FV430 but with a fully rotating turret at the rear housing the 105 mm gun and given the vehicle designation of FV433. Designed as a Sexton replacement, its correct designation was "Gun Equipment 105mm L109 (Abbot)". "L109" was little used, probably to avoid confusion with the 155 mm M109 howitzer that entered UK service at about the same time. The name "Abbot" continued the Second World War style of naming self-propelled artillery after ecclesiastical titles. The FV433 used a different configuration of power pack from other vehicles in the FV430 series. Development Ammunition A completely new ammunition family, comprising shells, fuzes and cartridges, was designed for Abbot's L13 gun, designated "105 mm Field" ("105 mm Fd"). It is separate loading cased charge ammunition (shell and cartridge loaded into the gun separately) with electrical primers, in contrast to the widely used semi-fixed US 105 mm M1 type ammunition (called "105 mm How" in UK service), which uses percussion primers, and has shorter shells. There were two versions of 105 mm Fd ammunition. Mark 1, which was used initially, had a UK-produced 105 mm How shell, mostly US pattern fuzes and reduced charge 105 mm Fd cartridges with their electrical primers. Mark 2 adopted a new projectile design, including an improved lethality high-explosive (HE) shell (heavier with more HE) and full charge cartridges. Its shell types include HE, Smoke, Coloured Marker (Red and Orange), Illuminating, and HESH for direct fire against enemy armoured vehicles. Direct Action, Controlled Variable Time (CVT) and Mechanical Time (MT) fuzes were available for HE and Coloured Marker shells. Initially, there were three cartridges. Sub-zones 1 and 2 were only used to provide short-range in high angle fire and were soon replaced by a plastic spoiler slipped over the shell ogive. Normal cartridge gave charges 1–5, each bag being a different colour in accordance with established UK practice, Mark 1 normal cartridge only went to charge 4. Both marks had charge Super, a single charge cartridge, although the charge was reduced in Mark 1. Charges 5 and Super used extended "bags" that projected beyond the metal cartridge case. The 105 mm Fd uses double (often internationally called triple) base propellants designated N in