[Berto]

Big bores in general, I'd be okay with. If fmj includes truncated flat point or copper washed wadcutters, then maybe those too in .38/.357.

 

[Berto]

I also agree that fmj might have advantages in mouse rounds up to .380acp. Older slow moving rounds like the .38SW did okay with long heavy for caliber bullets that frequently tumbled in tissue.

 

[Berto]

Well, if it's only about "feelings", then facts need not interfere??

FWIW, I look at ball/FMJ/non-expanding handgun bullets as essentially being the default "worst case" scenario for each caliber.

How much better than "worst case" would make you feel better?

Now, if you're looking to find a "caliber" answer to somehow not making "worst case" the worst case? Dunno how to spin it.

I remember having this conversation with a good friend of mine once, when the subject of permitting ball loads for off-duty .380ACP users. he was the current range master for a medium-sized agency, and had also served as a detective for major crimes, special enforcement bureau, etc. His answer was basically that if someone could take advantage of potentially seeing expansion, meaning using some type of JHP, why wouldn't they want to take advantage of it? Yes, the arguable variability of penetration differences was also discussed, but the "advantage" ultimately went to a properly designed JHP, overall. That was one man's opinion.

Personally, even though I'm no longer working under the ammunition requirements of my former agency, I'd typically prefer to save the ball ammo I've set aside in various calibers for the firing range, and use the JHP's for retirement CCW use. I own 9 pistols chambered in .45 ACP, too. Now, if any of those .45's hadn't been demonstrated to be reliable in their feeding of JHP ammo, and couldn't be made reliable with the use of some particular JHP load? I'd probably mostly be carrying the other .45's that would reliably feed JHP loads. This isn't the 60's & 70's anymore.

I always appreciate your detailed, thought out replies.
I differ a little regarding .380 and lesser cartridges; I've had a number of small .380 (and a few .32acp) pistols over the years. The first was an AMT backup DAO, it was a ' difficult' gun, but I shot it frequently
into various chunks of wood, siding, steel roofing materials, wet phone books etc...completely unscientific useless and not always reflective of terminal performance in people folks....but it was fun and there was lots of stuff around the property.
I did learn the gun wouldn't run on anything but ball ammo. Ball ammo worked and generally went through stuff about like my .38 snubby with soft lead swc did.
Jhp didn't run, and they didn't penetrate very well even when they didn't expand because being lightweight short bullets, they'd break apart sometimes (low SD).
I recalled some LE friends mentioning this issue with .380 and even some 9mmP (95gr) bullets particularly with big bones.
Granted, this was years ago, and pretty much everything was cup and core 88-90gr jhp's or ball.
These days, I feel like it's more or less a wash between a good jhp load like the better xtp loads or the new 99gr HST -and ball at least in tiny guns, like the Elsie or BG380 types. Going up to 3+" blowback guns like the Walthers PP types gives .380 enough of a lift in velocity to get consistency.
Splitting hairs probably, and it's just a feeling, right?
Were I to try another small .380, I still feel like the tradeoffs are either/or with regards to expansion and penetration...enough to negate real advantages over ball ammo. I wouldn't even bother with it in .32acp.
I still look at the Kahr CW.380 at the shop, it's attractive, and I'd load it up with an xtp bulleted load....but ball wouldn't bother me at all in that gun either.