.276 inch Other
As well as the ball round, drill, dummy, blank and proof ammunition was produced based on the case of RL 18000C.
L. to R., Ball 18000C, Inspection, Dummy Drill and Winchester made .276 inch.
Although the outbreak of war had brought development of the .276 inch round to a halt, later in the war some work was carried out with armour piercing bullets. Problems were being encountered with German steel sniper plates and loop holes that were defence against the then current .303 inch armour piercing round, the Mark VIIP. It was suggested that the .276 inch round had the potential to improve penetration and so several bulets were designed.
In the event, this work was not completed as the introduction of an improved .303 inch armour piercing round, the Mark VIIW, overcame the problem.
Blank
A .276 inch blank cartridge was also produced to design RL20408.
The case was that of RL18000c but with the neck closed with a six petal crimp over two strawboard wads.
The propellant was 10 grains of sliced Cordite size 20.
Proof
Two proof cartridges were produced. The first was to design RL 18000.B(i) for use with pressure barrels and the second to design RL 18000.B(j) for proof of rifles.
No further details are known.