Several different loadings of the .5V/580 round were developed for British service, as follows:
Ball Mark I.z: 580 grain bullet with two-piece core (front aluminium, rear lead). Approved for service 1924, but not issued.
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Ball Mark II.z: 580 grain bullet as above, muzzle velocity 2,540 fps (774 m/s). Approved for service 1925.
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Ball Mark II (cordite propellant): approved for land service 1933.
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Armour Piercing W. Mark 1.z: bullet with hardened steel core and lead sleeve and tip filler. Approved for service 1925. To pass proof, seven out of ten bullets had to penetrate 18 mm of armour plate at 100 yards range at 0 (90) degrees, and 70% also had to penetrate 14 mm armour striking at 20 (70) degrees.
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Armour Piercing W. Mark 1 (cordite propellant): as above, approved for land service 1933.
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Semi Armour Piercing F Mark 1.z: bullet as AP except steel core not hardened. 2,470 fps (753 m/s). Approved for naval use 1938. To pass proof, 70% of bullets had to penetrate 15 mm armour plate at 100 yards and 0 (90) degrees.
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SAP Tracer FG Mark 1.z, II.z, III.z: bullets weighed 542, 549 and 515 grains respectively (35.1, 35.6, 33.4 g), all at 2,470 fps (753 m/s). They all had a steel core with a tracer cavity drilled in the base, and all traced to 800 yards (730 m); the Mks II and III had a dark trace (i.e. tracer did not illuminate until 100 yards from muzzle). All were approved between 1940 and 1944. All had to achieve the same penetration figure as the SAP F Mk 1.z.
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Incendiary B Mark I.z: bullet weighed 562 grains (36.4 g) and was similar in design to the .303 inch B Mk. VII (i.e., a simplified "De Wilde"). Within the jacket was a steel sleeve containing 28 grains of incendiary composition with a further 2 grains of QF composition held in the jacket tip. Introduced after 1939.