Info to consider

Brandon at ammunition to go sent me results of gel tests they performed on handgun ammo. In all they tested 93 different loads. Many of us have weapons for self or home defense. When it comes down to the wire, you want to inflict enough damage to stop the threat in the least time possible. The fewer shots you need to fire means more rounds remaining should your threat have help.
9mm
45ACP
40S&W
380 auto
Of course, all rounds are not created equal. Even if a .45 does not penetrate as deep as a 9mm, it has a lot more energy to transfer given that most are double the weight. Hopefully these tables can help you and me in deciding what rounds within our caliber of choice will best match our purpose.