They won't stabilize properly, so you won't have any accuracy.
The twist rate needed for a particular bullet is actually based on the length of the bullet, not the weight. But when you are comparing copper-covered lead bits of exactly the same diameter, extra length means extra weight, so we know that a 69 grain .224" bullet is longer than a 55 grain .224" bullet. It's easier to talk about weight.
However, steel is less dense than lead, so a 62 grain .224" steel-core bullet is longer than a 69 grain .224" lead-core bullet. And the longer bullet needs a faster twist rate to stabilize properly.