Reasons i always load good JHP for carry:
1. Pistols SUCK for stopping power, relatively speaking. Caliber arguments are generally pointless, IMO, as any round capable of developing enough energy to reliably incapacitate in one or two rounds would be far too powerful to be controllable in a firearm that's readily concealable for civilian carry. That being the case, when a relatively slow bullet passes through tissue, it only damages tissue that it comes in direct contact with, which means that, while shot placement is the most critical factor, if you can increase the cross-sectional area of the projectile, it improves your chances of hitting something vital.
2. Even if a JHP bullet fails to expand, assuming weight and velocity are the same, it's WORST CASE scenario performance is that it will perform exactly like an FMJ bullet. After all, JHPs don't get any smaller when they don't expand.
3. Most pistols designed or built since the late 70s or early 80s have been designed to reliably cycle JHP rounds...and modern JHP rounds typically have an ogive and cavity meant to be useful even in guns NOT designed for them. I have never personally experienced a malfunction in a handgun directly attributable to using JHP vs FMJ bullets, even in my 1911. Though, admittedly, it is a modernized version of a 1911.
TL;DR version, unless your firearm has exhibited any sort of unreliability when loaded with JHP bullets, there's really no good reason apart from price and availability to use FMJ instead of JHP in a modern, decently made handgun.
Just my opinion, of course, but an opinion supported by a lot of evidence on the part of people who learned the hard way. Not me, fortunately, but if my a$$ is ever on the line, i want every advantage i can get...
