<P> The chosen new penetrator material, tungsten carbide, was too heavy at full bore to be accelerated to a sufficient muzzle velocity . To overcome this, a lightweight full diameter carrier shell (APCR) was developed to sheathe the inner high density core . However, the low sectional density of the APCR resulted in high aerodynamic drag . Instead, the British devised a way for the outer sheath to be discarded after leaving the bore . The name given to the discarded outer sheath was the sabot (a French word for a wooden shoe, also used to describe the standardized wood or paper - mache wadding around round shot in a smooth bore cannon). </P> <P> Armour - piercing, composite non-rigid projectile design was a high density core within a shell of soft iron or other alloy, but fired by a gun with a tapered barrel . The projectile was initially full - bore, but the outer shell was deformed as it passes through the taper, leaving the projectile with a smaller overall cross-section and giving it better flight characteristics . </P> <P> The Germans deployed their initial design as a light anti-tank weapon, 2, 8 cm schwere Panzerbüchse 41, early in the Second World War, and followed on with the 4.2 cm Pak 41 and 7.5 cm Pak 41 . Although HE rounds were also put into service, they weighed only 93 grams and had low effectiveness . The German taper was fixed on the barrel . </P> <P> In contrast, the British used the Littlejohn squeeze - bore adaptor, which could be attached or removed as necessary . The adaptor extended the usefulness of armoured cars and light tanks, which could not fit any gun larger than the QF 2 pdr . Although a full range of shells and shot could be used, changing the adaptor in the heat of battle was highly impractical . </P>

What type of gun fired shells in ww1