Editing Armour-piercing ammunition (section)

=== APCR/HVAP ===
''Armour-piercing composite rigid'' (''APCR'') in British [[nomenclature]], ''high-velocity armour-piercing'' ('''HVAP''') in US nomenclature, alternatively called "hard core projectile" ({{langx|de|Hartkernprojektil}}) or simply "core projectile" ({{langx|sv|kärnprojektil}}), is a projectile which has a core of high-density hard material, such as [[tungsten carbide]], surrounded by a full-bore shell of a lighter material (e.g., an [[aluminium]] alloy). However, the low [[sectional density]] of the APCR resulted in high [[aerodynamic drag]]. Tungsten compounds such as tungsten carbide were used in small quantities of inhomogeneous and discarded sabot round, but that element was in short supply in most places. Most APCR projectiles are shaped like the standard APCBC round (although some of the German ''Pzgr.'' 40 and some Soviet designs resemble stubby arrows), but the projectile is lighter: up to half the weight of a standard AP round of the same calibre. The lighter weight allows a higher muzzle velocity. The kinetic energy of the round is concentrated in the core and hence on a smaller impact area, improving the penetration of the target armour. To prevent shattering on impact, a shock-buffering cap is placed between the core and the outer ballistic shell as with APC rounds. However, because the round is lighter but still the same overall size it has poorer ballistic qualities, and loses velocity and accuracy at longer ranges. The APCR was superseded by the APDS, which dispensed with the outer light alloy shell once the round had left the barrel. The concept of a heavy, small-diameter penetrator encased in light metal was later employed in small-arms armour-piercing incendiary and HEIAP rounds.