The damage caused by a solid projectile can be roughly approximated with its kinetic energy, since all of that energy will be dissipated into the target on impact (in an ideal scenario, ignoring complications such as overpenetration depending on the properties of the projectile vs. the properties of the target). The general case of this makes intuitive sense. If you make a bullet go faster, or make it heavier, it will "hit harder".
However, what about the kinetic energy from the projectile rotating on its axis of flight? If you purely make a bullet spin faster, without altering its velocity in the direction in which it impacts the target, will it actually do more damage? It definitely has more kinetic energy, and the kinetic energy should also be imparted into the target on impact.
But intuitively it doesn't seem like e.g. a 5g bullet flying at 1000 m/s spinning at 1 000 000
600 rpm would "hit harder" than a 5g bullet flying at 1000 m/s spinning at 350 000 300 rpm.
Edit: amended example values for rpm