The projectile does not go that fast, of course, but an internal "shaped charge" accelelerates a portion of the projectile to that speed upon impact. This effect has nothing to do with bullets penetrating steel.
True with a HEAT round, but not with a Sabot. The sabot rounds DO go approximately that fast, and will completely penetrate a T54/55 purely on kinetic energy alone. Seen it myself....
John
