Personally, I still think it sounds like a solution in search of a problem.
I’ve shot the Glock 21(.45 ACP) and it’s noticeably thicker than the 17/22 pistols. For my average size hand, it was still shootable but not really comfortable.
Which is basically the reason for most wildcat loadings. 
My thoughts:
[ol]
[li]I’d hate to spend $2-4 a bullet to own a weapon[/li][li]It takes all of teh fun out of target shooting when my wrists are sore three or four days.[/li][li]It only comes in stainless and I like my weapons to be low-visibility.[/li][li]I don’t live anywhere near Kodiak bears or Cape Buffalo so it would be next to useless.[/li][/ol]
My Beretta 96D and my Remington 870 are enough to handle 90% of the problems out there. Running away while take care of the remainder.
Heck, my Ruger 22/45 target pistol is enough to handle 90% of the problems out there. As an expert once said “A well placed shot from a .22 has more stopping power than a wild miss from a .45”.
I would agree with this. I think most shooters know at least one guy who’s spent ages perfecting his own custom cartridge which is ballistically very similar to one you can buy commercially, but not interchangable with it or anything else in existence.
Actually, now I think about it, it’s possible wildcat cartridge developers might be the original hipsters.
Minor rant. When I was reading gun mags from the 60s and 70s, ‘ACP’ stood for ‘automatic centerfire pistol.’ Now, all online sources say the ‘c’ stands for ‘colt.’
It always has. They just didn’t know any better. Hell, the original, now antique, ammo boxes don’t even say ACP. They read .45 Caliber M1911. Later boxes, from the era you’ve mentioned, are labeled 45 auto.
I’ve never seen any cartridge besides those originally designed for a Colt self-loader designated “ACP”, and it’s worth noting all semi-auto pistols were centrefires around that time.
I’m not actually sure when the first semi-auto .22 pistols came about but I’ve never seen one from before the 1920s or so - semi-auto .22 rifles were around from the early 1900s, though.
British publications from the 1920s-1950s variously refer to the .45 ACP cartridge as “.45 US Government”, “.45 Auto(matic)” and “.45 Automatic Colt’s Pistol”, FWIW.
The line of “ACP’s” include: .25, .32, .380, and .45. The .38 super (9mm long) never had the ACP attached to it.
No, but as far as I can tell, the .38 ACP, aka .38 Auto, was the predecessor to .38 Super (Automatic). The main difference is the power/pressure. .38 ACP is rarely used now; .38 Super is used in competitions or in places that forbid .45 and used in 1911s etc.
Just to be really confusing, there’s also a .380 ACP which is still manufactured but is in no way interchangeable with .38 ACP.
And I know .38 Super is popular with IPSC shooters in Australia because of the restrictions of .45 calibre handguns, but otherwise I’ve never seen a “normal” (ie not specially designed/modified for competition) handgun in the calibre, although I’m aware it was briefly popular in the 1930s before .357 Magnum came along.
It’s also popular in countries that prohibit civilian ownership of firearms chambered in “military calibers.” IIRC, Mexico used to have quite a few, mainly 1911-style pistols. Not sure if Browning Hi-Powers were also re-chambered there to 38 Super.
Don’t many of those countries define “military calibre” as anything over a certain size (often .32 ACP/.32 S&W Long), though?
I had heard .38 Super was popular in Mexico because of their laws, though.
Or wider!
except maybe a revival of the Vietnam tunnel gun.
http://www.barthworks.com/military/guns/photos/s%26wtunnelgun.jpg