[hogwiley]

People tend to overthink handgun stopping power. It's actually pretty simple.

Handgun bullets don't travel fast enough to cause a temporary stretch cavity violent and large enough to significantly damage surrounding tissue, while high powered rifle rounds DO.

So handgun rounds cause damage by direct crushing of tissue. As a result, if average penetration depth is approximately the same, the handgun round which has the largest diameter and frontal mass and creates the larger wound channel for the longest length of its travel through the body, will cause the most damage and therefore be the most effective, all other things being equal. It will damage more blood vessels and nerve tissue and marginally increase the likelihood a "vital" organ or vessel is damaged.

Frontal mass and weight also impact the damage done to bone. A larger diameter and heavier bullet will tend to do more damage to bone than a smaller lighter bullet. Again, were talking at handgun velocities. It can mean the difference between a bullet grazing the skull and instead causing a skull fracture, or a bullet glancing off of or lodging in say a femur bone, and actually breaking a femur, or a pelvis. All of this can make the difference in whether someone is "stopped" or continues on for the immediate future.

This is why I personally prefer .40 and .45 for home defense. For carry ,considerations are different, because concealability and weight matters more, as does ammo capacity(in certain situations).

The .40 is still my preferred round because it still offers nearly the same capacity and size of a 9mm gun while firing a larger and heavier bullet, with a larger diameter hollowpoint cavity resulting in more reliable expansion. The argument that certain bullet designs in 9mm completely closes the gap makes no sense to me, since you could also use that same design in a larger caliber, thereby keeping the gap.

Cops are moving back to 9mm again because heavier weights penetrate into cars a little better, its easier to shoot(especially for women), cheaper, and causes less wear and tear on a gun, and gives more capacity. NOT because its completely equal in all situations to a .40, as some people seem to suggest.