Over-penetration is a misplaced fear.
Aside from the fact that the occurrence of over-penetration would be very unlikely to have a negative effect (low probability of innocent strike vs. high probability of faster bleed-out due to 2 holes instead of one), over-penetration occurs for an entirely different reason than most people think.
Over-penetration is caused by the failure (or lack of design capability) of a projectile to expand, fragment, or tumble terminally in order to expend its kinetic energy rapidly. This failure is most commonly the result of clothing barriers clogging the hollow-point, or too-low of an impact velocity. Higher velocity actually increases the odds of a projectile to overcome the elastic resistance of a given medium, and its own structural integrity, thus decelerating rapidly while expending its energy through wider-spread disruption of the medium. Velocity is not proportional to penetration unless using projectiles which do not expand or lose stability upon impact.