There are a ton of different loads available in either platform, semi auto or revolver. If you are an inexperienced shooter and your wife may be required to use the gun, a six shot revolver chambered in .38 spl. will do the job nicely. It's point and shoot simplicity, threat ending power, and lack of overwhelming recoil and muzzle-flash make it a no brainer! If you are more experienced, any quality semi-auto with larger than a .380 acp. but smaller than .50ae. will suffice. With whatever weapon you decide on, practice- practice- practice and take time out to learn the laws governing the use of deadly force in your state.