Handgun rounds don't have the velocity to plastically displace the tissue of a body like rifle rounds do. As long as you get something that's effective enough, I think it is worth it to carry more ammo in a lower recoiling caliber, if able. Higher velocity, lighter rounds will do more damage to an opponent, while also fragmenting or stopping faster after hitting a barrier like a wall in you or someone else's house.
15 rounds of 115gr 9mm hollowpoint are going to recoil less than, and give you more opportunities to get a good hit with, than .38 Special.
But, if you're at a wedding and want a pocket gun, maybe a snub-nose .38Spl is the best solution.
Some research of self defense and police shootings led me to some ROUGH conclusions. These could be way off, but seemed to be some very general and semi-consistent conclusions.
- Most people would draw a firearm in self defence in their life if they had one on them
- over 99% of the time a gun is drawn, no round needs to be fired. The gun itself controls the situation.
- Of the times the gun needs to be fired, frequently everything in the gun will be fired, regardless of capacity.
- Of the times someone shoots back, frequently every round available on the person is fired.