Finding the right type of ammo can be a bit of a process and semi expensive if you have to buy multiple boxes of self-defense ammunition. Over the years, I have met more than my fair share of individuals who don’t think self-defense ammunition is important and just think ball ammunition is fine. Now there are a few different studies out there which show 45 ACP ball rounds transfer the majority of their energy into a body, but other calibers, especially 9mm, won’t transfer their energy and will simply blow through the body.