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The nomenclature of the .50 inch Browning Armour Piercing rounds is somewhat complicated with two different rounds occupying the W Mark Iz slot as explained below.
Armour Piercing W Mark Iz
"Cartridge S.A. Armour Piercing .50 inch Browning W Mark Iz" was the American M1 AP round and included the Remington made contract ammunition. Britain purchased .50 inch ammunition both from the American government (via the U.S. Steel Corporation) and on contract from Remington for the RAF, some of which was specially marked to British requirements. Large quantities were also supplied under Lend Lease.
It was declared obsolete in Lists of Chages dated June 1948.
The cases were standard .50 Browning with Boxer primers. If from American government stock a typical headstamp was "50 CAL FA 39". If from the Remington contract the early rounds were marked "R A 40" whilst later rounds were specially headstamped "RA 1941 .50 CAL Z"
The bullet had a gilding metal envelope with a hardened steel core and a lead tip filler with no sleeve. Weight was about 750 grains.
U.S. Government supplied rounds had a black bullet tip whist the Remington contract ammunition had a green bullet tip.
Muzzle velocity was 2,500 fps with a charge of about 240 grains of nitrocellulose propellant and penetration was 1/2 inch of armour at 1,000 yards.
1940 Remington contract label showing overprint of "GREEN" for the tip colour.
1942 Remington contract label specially printed for RAF.
Armour Piercing W Mark IIz
"Cartridge S.A. Armour Piercing .50 Browning W Mark IIz" was approved to Design DD/L/12676 in December 1942. It was the British made equivalent of the Americam M1 round. It appears that very few were made, if at all, as no surviving specimens are known. It was listed as obsolescent in 1949.
The case was a standard .50 inch Browning but fitted with a Berdan primer. The headstamp bore no Mark numeral and was typical ly "SR 43 .50". The case should have a green primer annulus.
The bullet was boat tailed with a gilding metal envelope and a hardened steel core and lead tip filler without a lead sleeve. The weight was 759 grains. The bullet tip should be coloured green.
Armour Piercing W Mark 1z
The next mark of armour piercing cartridge should logically have been the W Mark 3z, but was given the title of W Mark Iz, the same as the original American made ammunition. This may have been because the original W Mark Iz had already been declared obsolete, but is unusual
"Cartridge S.A. Armour Piercing .50 inch Browning W Mark 1z" was approved to ICI Drawing BK 261/53 in 1952. It essentially replicated the American M2 armour piercing round.
The case was a standard .50 inch Browning but was fitted with a Berdan primer. It was only made by ICI Kynoch and the headstamp usually bore the Mark numeral, typically "K.53 .50 W1Z". The primer annulus was green.
The bullet was boat tailed with a hardened steel core and lead tip filler without a lead sleeve, Weight was 710 grains and had a green bullet tip for identification.
Ballistics were similar to the American M2 round, with a muzzle velocity of about 2,800 fps.
British label for .50 inch Browning AP rounds. The Mark number is uncertain.
Experimental Designs
A great deal of effort was made during WW2 to improve the armour piercing capability of the .50 inch Browning., both by using conventional designs and also solid shot.
The conventional designs were all broadly similar with a hardened steel core and lead tip filler, differing only in the weight and size of the core.
These were:
DD/L/11826 Weight 705 grains
DD/L/11826A Weight 700 grains
DD/L/11826B Weight 740 grains
DD/L/11832 Weight 674 grains
DD/L/11834 Weight 700 grains
DD/L/12676 Weight 760 grains. This was based on the American M1 AP round and became the W Mark IIz
A further Kynoch design, TS.11995A, (later redrawn as BK 167/217A) was tested in 1941. This was flat based with either a CNCS or GMCS envelope and weighed 680 grains.
A large number of solid shot designs were produced, perhaps twenty in total, some having a tracer in the base of the shot. Most were of normal pointed shape but DD/L/1003 was flat nosed and DD/L/1004 round nosed. Some had a plastic windshield crimped to the front of the core.
Three solid shot designs. The design number of the two left hand items is unknown but the right hand one is DD/L/1004,
Further solid shot designs (design numbers unknown). Second from right is missing its plastic windshield.
In addition to the solid shot designs, there were a number of composite rigid AP (C.R.A.P.) designs, having tunfsten cores in an aluminium sabot with copper base caps.
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