The FBI suggests a minimum of 12 inches penetration in 10-percent ordnance gelatin for law enforcement ammunition. Penetration this deep is not hard to achieve with defensive handgun cartridges—until you also mandate the bullets expand, too. The more a bullet expands the less it penetrates. But, the more a bullet expands, the bigger the hole it makes. Defensive handgun ammunition engineers strive for an optimum balance between expansion and penetration.
With its Critical Defense ammunition, it appears Hornady has established the maximum amount of expansion it can achieve with each load and still obtain about 10 inches of penetration in 10-percent ordnance gelatin at standard velocities. This is less than the FBI mandate, but Critical Defense ammunition is not intended for law enforcement. It is purpose built for the armed citizen carrying a compact handgun to fight off an attacking criminal. Since most bad guys do not assault law-abiding citizens in the nude, Hornady wisely designed Critical Defense ammunition to work on criminals who like to wear clothes.