cartridge in its brass case was loaded and the breech closed. In British terminology, the 25-pounder was called "quick firing" (QF), originally because the cartridge case provided rapid loading compared with bag charges, and was automatically released when the breech was opened. The use of separate shell and cartridge allowed the charge to be changed for different ranges. For the Mk 1 Ordnance on an 18-pounder carriage there were three "charges", charges one, two and three, all of which could be used in the common cartridge design. The Mk 2 Ordnance on Mk 1 carriage added a "super" charge in a different cartridge. In 1943 a separately bagged "increment" charge was added; used with the Super it provided higher velocity for anti-tank use. The introduction of the increment to super was only possible following the addition of the muzzle-brake in the previous year. Subsequently, another type of increment was introduced to be added to charges one and two to provide additional combinations for use in high angle fire. However, this fire required a dial sight adaptor, removal of the platform and some excavation of the ground. In common with all British guns of the period the indirect fire sight was "calibrating". This meant that the range, not elevation angle, was set on the sight. The sight compensated for the difference in the gun's muzzle velocities from standard. The gun was also fitted with a direct-fire telescope for use with armour-piercing shot. It also used "one-man laying" in accordance with normal British practice. An important part of the gun was the ammunition trailer ("trailer, artillery, No 27"). The gun was hooked to it and the trailer hooked to the tractor for towing. The gun did not need a limber and could be hooked directly to a tractor. The trailer provided the brakes as only a hand-brake was fitted to the gun carriage. The trailer carried ammunition; thirty-two rounds in trays (two rounds per tray) in the trailer protected by two doors. Ammunition was also carried in the gun tractor with the detachment and various gun stores. Some stores, such as sights, were carried cased on the gun. Each section (two guns) had a third tractor that carried ammunition and towed two ammunition trailers. The gun detachment comprised the following: No 1 – detachment commander (a sergeant) No 2 – operated the breech and rammed the shell No 3 – layer No