Home defense ammunition must be chosen on a basis of reliability and cartridge integrity. The ammunition must always feed in a self-loading action gun. Revolver loads must have a good crimp to properly chamber and maintain bullet pull during firing of heavy recoiling loads. Only after reliability is established do we consider the performance of an individual loading.
Wound ballistics should include a good balance of expansion and penetration. The cartridge must exhibit good accuracy and a minimal muzzle blast, which is a product of a full powder burn.
While accuracy is important, most handguns will place all their ammunition in single ragged bullet hole at 7 yards. Studying wound ballistics for over three decades, I know that penetration is the single most important factor for wound potential. When a small-caliber handgun performs beyond expectation, it is because of good penetration. When a big-bore handgun fails, it is usually because of poor penetration or shot placement. The projectile must penetrate 12-16 inches in water or ballistic gelatin to reach the vitals and produce blood loss in the body’s pressurized system. Expansion to 1.5 times bullet diameter is desirable. A round nose lead or full metal jacketed bullet simply presses flesh aside or creates a small puncture wound. A hollow point or blunt nosed bullet cuts and excises a larger area, resulting in more damage.
Too much penetration isn’t desirable for home defense and neither is a bullet that tends to deflect from bone or hard surfaces.