US Projectile, 1.1 inch AA, Mk 1 Mod 0 - 28, Mk SD 1
The 1.1 inch Mk 1 is not self-destroying; the 1.1 inch Mk SD 1 is self-destroying. This is the primary difference between the two projectiles.
The Mk SD 1 consists of a Mk 1 projectile body modified for self-destruction by drilling through the wall between the tracer and HE cavities.
The Mk 1 projectile may also be issued BL & T for target practice or de-icing.
The 28 Mods are to distinguish among contractors.
Nothing else to see.
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