The Mod 8 has a heavier cap, blunter nose, and more hardness, from greater heat treatment than the earlier Mods.
No information about functioning.
Projectile, 16 inch Target, Mk 9 Mod 1, 2
Projectile, 16 inch Target, Mk 10 Mod 0
OP 1664, Volume 1 - US Explosive Ordnance (1947)