Cartridge, 40 mm: L/60 AP-T

seconds after firing. The cartridge case is crimped rigidly to the projectile by one or two 360º crimping bands; weapons using automatic feed systems or guns with increased rate of fire modifications should use double-crimped ammunition. The brass cartridge case, which can be reused several times if required, has a semi-rimmed base and is fitted with a percussion primer with a sinoxide detonator. Propellant loads vary from manufacturer to manufacturer, but the Bofors 40 mm L/60 AP-T uses approximately 320 g of NC 1066 single-base low-erosion propellant, producing a muzzle velocity of 860 m/s. As a further rough guide to other similar 40 mm L/60 AP-T rounds, the US M81 and M81A1 AP-T round cartridge case (the M25 or M25B1) contains approximately 295 g of M1 propellant. This produces a muzzle velocity of 875 m/s. On impact with the target the steel windshield crumples to allow the penetrator to pierce the target armour. The Bofors 40 mm L/60 AP-T can penetrate 40 mm of armour plate set at an angle of 60º at a distance of 100 to 150 m. The 40 mm L/60 AP-T round was originally developed just prior to or during the Second World War, providing the Bofors 40 mm L/60 anti-aircraft gun with a capability to defeat armoured land targets. It is still deployed to penetrate the protection carried by many modern strike aircraft and helicopters. Applications include all 40 mm L/60 Bofors Guns.