[dragonwriter]

> My understanding is that hollow points were designed to prevent over-penetration rather than to harm more

The reasons they were designed to prevent overpenetration is because:

(1) overpenetration means energy which could go into damaging the target is instead wasted doing something else, and,

(2) that “something else” is sometimes harming things that one doesn't mean to harm.

[Casseres]

Is (1) a by-product of (2), or is (2) a by-product of (1)?

Some people are arguing that hollow points were designed for (1), causing the most damage, and that (2), stopping in the target, is just a side-effect of its true purpose.

[dragonwriter]

> Is (1) a by-product of (2), or is (2) a by-product of (1)?

No, both are essential and important factors in what motivated the development of hollowpoints. The idea is both to maximize effectiveness against the intended target and minimize collateral damage; almost any time you have any justification to use a firearm the first is of central importance, and while the second may be less consistently important it is frequently important and overwhelmingly so when it is.