US Projectile, 3 inch Illumination, Mk 21 Mod 1, 2, 3
This is a spin stabilized, illumination projectile. The illuminating projectile is a thin case with a very small expelling charge just behind the fuze and an interior assembly of a star or candle with a parachute and a very lightly held base plug.
Fuzing consists of nose time fuze only.
The projectile body is light blue with two white stars.
Nothing else to see.
Collaborative Ordnance Data Repository