.5 inch Vickers Semi Armour Piercing Tracer

Semi Armour Piercing Tracer

The origins of the .5 inch Vickers semi armour piercing tracer rounds were a private design by Kynoch which they offered to the War Office in 1935 as they were also involved with trials of .5 inch tracers. In the event, no tracer round was approved for service but the semi armour piercing tracer tests were successful and eventually three marks were approved for service. The principal use was in the multi-gun anti-aircraft equipment on Royal Navy ships.

"Cartridge S.A. Semi Armour Piercing Tracer .5 inch FG Mark Iz" was approved for Naval service in February 1940 to Design

The headstamp included the code "FG" and the primer annulus was green.Proof was seven out of ten shots should penetrate 15mm of armour plate at 100 yards at normal angle of attack.Right: File card from Experimental Establishment Pendine showing early experimental brilliant trace SAP Tracer, probably made by Kynoch.The FG Iz served for most of the war but a dark ignition tracer was required so "Cartridge S.A. Semi Armour Piercing Tracer .5 inch FG Mark IIz" was approved for Naval service in late 1944 to design NOD 6325 and shown in LoC Paragraph B.9982 dated November 1944.In most repects it was similar to the preceding mark, although the bullet was slightly heavier at 549 grains. It had a 100 yard dark ignition and then traced to 800 yards. Propellant and muzzle velocity were as the Mark FG Iz, as was the penetration proof.

The headstamp included the code "FG" and the primer annulus was green.

Shown in the same LoC Paragraph was "Cartridge S.A. Semi Armour Piercing Tracer .5 inch FG Mark IIIz" with the same Design reference, NOD 6325.

The bullet of the FG Mark 3z was shorter than previous marks and weighed 515 grains. It only had a single cannelure and a slightly degraded ogive of 4.5 CRH. Presumably this was to match the trajectory of other loads better at long range.The propellant charge was 132 grains of nitrocellulose.

The headstamp included the code "FG" and the primer annulus was green.

In addition to the penetartion proof, seven out of ten shots had to have dark ignition to 100 yards +- 40 yards and then trace to 800 yards.

Few FG Mark 2z or 3z rounds seem to have been made as by late 1944 the Vickers anti-aircraft equipments on most Royal Navy ships had been replaced by 20mm Oerlikons.