The gun’s job is to launch the bullet. The bullet is what neutralizes a threat. That’s why picking the proper projectile is key.
In an urban environment where upright two-legged predators are the threat, a good choice is ammo with premium jacketed hollowpoint bullets. They expand upon entry to increase tissue damage, while reducing the risk of over-penetration that could harm innocent bystanders. This is the reason law enforcement agencies use them. So should civilians, whether for concealed carry or home defense.
A number of trusted manufacturers offer premium hollowpoint bullets. Speer, for example, offers them in their Gold Dot line. Federal offers the HST and Hydra-Shok loads. Remington has the Golden Saber. Winchester uses the Ranger, and Hornady has their Critical Defense line. These are available in all of the popular personal-protection calibers under various personal-defense product labels.
For a walk out in the woods where the four-legged variety of predators can be a threat, the situation is reversed. This bullet needs to maintain as much of its weight and profile as possible order to punch through bone and deliver a central nervous system (CNS) hit. Semi-wadcutter designs cast from hardened lead, or softpoint bullets with a heavy copper jacket, are the most effective. All these loads will be found in the hunting product lines from the above companies.