imported post
May I suggest doing a 'net search for "ballistic gel studies"...?
Going here:
http://www.mouseguns.com/amball.htm
will give you plenty of info to look up.......
Modern jacketed hollow point (JHP)
self defense ammunition all share the same criteria of penetrating 12 to about 16 inches. It is designed to fully expand and stop penetrating somewhere between those two distances for one specific reason... to stay inside the bad guy shot thereby dumping all the energy and creating the most damage.
Obviously staying inside and dumping all the energy while doing the most damage will enhance the chances of causing a bad guy to stop attacking... but a jacketed hollow point (JHP) bullet by expanding and staying inside will also prevent, or dramatically lessen, the chances of the bullet going right on through and hitting an innocent standing behind the bad guy. And, bullets being bullets in that they can travel very long distances, the innocent might not be standing directly behind the bad guy but might be many yards away... but still get hit, and injured, by a bullet that went right through the bad guy. Remember... we are legally liable for each and every bullet that comes out of our guns regardless of where they go.
And ball, or round nose, or as it is commonly called... full metal jacket (FMJ)... bullets are prone to going right on through the bad guy.
So please allow me to suggest researching then choosing the best performing JHP bullet design that will cycle through your gun reliably (test fire several magazines full before carrying it just to make sure your gun will work reliably with that ammo please!) and leave the FMJ ammo for range work.
And please do not fall for the erroneous line of thought of buying a cheap self defense ammo hoping to save a few pennies... buy what will work best in your gun while providing the best defensive performance. After all... it would be terrible to have your ammo let you down and your last thoughts are.... "Well, at least I saved $15 on that box of ammo."