Strongly disagree Dave, the best way to stop a bad guy with gunfire is to hit vital structure in their body with your bullets, they do not need to go all the way through in order to accomplish this.

Ditto the comments above ref RNFMJ vs FMJFP/semi-wadcutters, in my experience they bring little or nothing to the table while also normally penetrating more than RN bullets.
One is FAR better off using modern premium JHPs for defense than using ball, be it RN or flat point.

I don't consider an exiting bullet necessarily "overpenetration", but ball rounds tend to be dangerous way downrange after going through people.

Our duty ammo here, the 124gr +P Gold Dot 9mm, normally goes all the way through on a torso shot but then will be caught up in the clothing or pop out and drop to the ground 5-10 feet behind the bad guy.