I won't quote the comments I disagree with but we'll discuss some of them here.
.380 ACP
.380 ACP has come a long way with better hollow point designs, as did 9mm 30 years ago and it's an acceptable self defense round, despite the lingering caliber snobbishness here in the US that decrees anything less than 9mm Luger isn't sufficient.
I have both a Kimber Micro and a Kimber Micro 9. The .380 ACP Micro has more tolerable recoil and more likely to encourage more practice. More importantly the Micro in .380 can be recovered faster under recoil allowing you to get more A zone hits in the same period of time than it's slightly larger Micro 9 sibling.
.32 ACP
.32 ACP hollow points have made much of the same progress as .380 hollow points. The 60 gr XTP will penetrate 12-13" and expand reliably provided you launch it from a 4" barrel at velocities of at least 1050 fps (and 1050-1100 fps is the norm with the Fiocchi load) - just like the 90 XTP in .380 ACP.
The 60 gr Hornady Critical Defense expands reliably as well at 4" velocities around 1000 fps and penetration is still 10-11".
Similarly, the Speer 60 gr Gold Dot gives pretty reliable expansion and 10" penetration when launched at 4" 1000 fps velocities.
Some self defense "experts" will say that isn't sufficient, but armed citizens are not shooting fleeing felons at odd aspect angles and are almost always going to to be shooting in a face to face aspect engagement where 10-11" is plenty.
When you further consider that about 95% of all self defense uses of a handgun don't involve actually firing the handgun, and that in the remaining 5% the assailant stops the assault as soon as he or she is shot about 50% of the time regardless of caliber .32 ACP is clearly good enough.
There's also some interesting data out there showing higher stop rates for .32 ACP than for 9mm, although there are several confounding variables in the mix, such as experience/skill of the .32 ACP shooter, use of FMJs in the 9mm, etc.
In the right hands, .32 ACP will get it done and when compared to the .380 ACP in the same model pistols it usually offers 1 more round in the magazine and will enable a well trained shooter to get more A zone hits in the same period of time than the same shooter and pistol in .380 ACP.
.32 ACP is also very recoil friendly and is a good choice for a female shooter with small hands or a geriatric shooter with arthritis who might not otherwise be interested in both carrying a firearm and practicing with it. In the Beretta Tomcat, it is also an ideal choice for someone with limited hand strength who can't rack a slide.
The caveats here are that even more so than the .380 ACP the .32 ACP is takes a big hit in shorter barrels and with a 2.75" or 3" .32 ACP don't bet on getting consistent expansion. But on the other hand when you don't, that failed to expand hollow point will act just like an FMJ.
From that perspective 71-73 gr FMJs or 73-75 grain hard cast bullets only make sense for a shooter with a shorter barrel and or who values penetration. A hot loaded 73 gr FMJ like the Fiocchi load at around 850 fps in a short barrel will still give 16-17" of penetration, and in a 4" barrel it will give 20-21" penetration in ballistic gel.
.25 ACP
Forget expansion and don't bother with anything other than a 50 gr FMJ. But that said, even a Beretta 950, 950B or 950BS will give you 12" penetration in ballistic gel. By the 95%/5%/50% defensive handgun use data above, it's still sufficient. Not anywhere near my choice, but it's a huge step up from nothing.
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Some of the newer cartridges.
.327 Federal
It's a great short barrel revolver round and offers a nice step up from .38 Special. But at present the effective self defense hollow point options are limited, if you're into the FBI ballistic gel standards. Still, the 100 gr Gold Dot does pretty well in both 2" and 4" barrel lengths and the 85 gr Hydra Shok isn't far behind.
It needs more ammo development, but sadly I don't think it's going to stay around long enough in sufficient numbers to get it.
.30 Super Carry
I don't have any direct experience with it and have not done any ballistic testing with one, so I'll refrain from commenting other than I'm not seeing the niche it is supposed to fill.
Still, weird things happen. For example the .350 Legend doesn't do anything ballistics wise that the .38-55 and .375 Win can't do as well or slightly better. But it's very popular in Midwest states because Winchester lobbied hard for straight wall "pistol" case rules that favor it, and it's popular elsewhere because it fits in an AR-15 upper and lower.
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Someone commented that we as Americans have a God given right to carry firearms. That's a dangerous belief to hold because it's just not true. Our 2A rights stem from a compromise made by the founding fathers to adopt the Bill of Rights as a necessary step in getting the Constitution ratified.
The 2A is a right given by humans that can be taken away by humans, and we need to be very careful never to forget that. We also need to understand that it's just an add on in a Constitution that was focused not on individual liberty but rather on creation of an environment conducive to commerce and acquisition of property.
That's never been more relevant than it is today with a legislative branch owned by big business and rich folks, an executive branch that is equally beholden to those same rich folks, and a judiciary that has become beholden to those same big money interests.
