US Cartridge, 20mm API-T, M601
The tungsten-carbide core is the main part of the projectile, and is the penetrator. The ballistic cap (ogive) contains an incendiary pellet. A tracer tablet is at the base of the projectile. The projectile body is painted black with white markings and with red painted "T's" encircle the ogive (signifying tracer).
Nothing else to see.
Collaborative Ordnance Data Repository