[Mello2u]

Penetration can be inversely proportional to velocity. It depends upon bullet design and performance.

For example, if a 230gr bullet hits a target at 1000fps (511 ft/lb) and deforms from its initial diameter of .45" to .60", its frontal area (.28 sq. in.; Pi R squared) will meet with a certain resistance and expend energy accordingly inside of the target.
If a .45" bullet is launched at 1300fps (863 ft/lb) and deforms to .80", its greater frontal area (.50 sq. in.) will meet greater resistance and transfer energy faster. With almost twice the area and less than twice the energy, it is logical that this bullet would penetrate less.

So it depends on how much energy is available and the rate at which that energy is transferred. It may be that the 1st example takes 16" to completely transfer the energy and the second example might transfer the energy in 12".