US Projectile, 3 inch AA, Mk 31 Mod 1
This projectile is specially cavitized to receive VT fuzes and their auxiliary detonating fuzes. No other fuzes may be assembled. Since VT fuzing is employed, no tracer is assembled; instead, the base is solid, and a special sheet steel base cover plate is welded on, 0.081 inch thick and 2.50 inches in diameter. This projectile replaces the original Mk 31 Mod 0, which has been recalled from service use. The Mod 0 was cavitized to receive the VT Fuze Mk 45 Mod 11, which differed from the Mod 12 by having a longer stem and has been declared unserviceable.
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