Sorry to be a wet blanket, but I just don't get that excited about wildcats based on usually already rare parent cases. Take the 375 JDJ which I think can be reasonably said to be the most successful of the JDJs. It's based on the 444 Marlin, which isn't even a common case, and is trouble enough to get your hands on, let alone potentially destroy in the conversion process.
Then start asking yourself WHY? How do any of the JDJ cartridges do something better than an already available cartridge? For example, is the 375 JDJ really an improvement over its parent, the 444 Marlin? Both cartridges are way overkill for deer, so lets focus on Elk. 444 Marlin, under 100 yards, offers better KO values. And beyond that, I really begin to doubt the wisdom of using a handgun. And 430 diameter has a much wider bullet selection than 375, too. To me a 375 JDJ makes MORE sense in a longer barreled rifle, like a re-barelled Marlin formerly in 444 than anything else.
The same goes for small bores it seems. Is there a small-bore JDJ cartridge that can do something the 7-30 Waters or 223 Rem can't?
I have owned several bizarre (44 Swiss), obsolescent (7.62x38R), and wildcat chambered firearms in my life, but now I've whittled it down to only one: 357 Herrett, based of the 30-30, and nearly perfect for whitetails. Common parent case, wide bullet selection (357/358, both pistol and rifle bullets), and no brutal recoil. I've fired a contender with a 375 JDJ and a X-Frame S&W in 500. No thanks!
But for those that like the JDJs, keep on enjoying them, anything that makes Contenders popular I support.
Awww c'mon curioushooter, where is your sense of adventure? Your name even says that you DO have SOME, so why not with JD's wildcats?
Seriously though, you are kinda stepping on a slippery slope so I will try and throw some sand under 'ya.
When JD Jones started experimenting and developing his cartridges, what he was really doing is wildcatting the most practical safe power in each caliber for hunting small and big game out of the small, light, almost elite Contender frame. Your argument about cartridges basically duplicating or overlapping other current cartridges (which weren't even neccessarily available in the CONTENDER way back then, as wvhitman said) is very weak. Look at today's lineup of rifle cartridges and what is popular! What does the 6.5 Creedmoore do.... blah blah blah what about the new Hornady cartridge ...blah blah... hey the new Weatherby .... and blah blah etc.
Part of it is marketing and of course stimulating sales, sure. But a large part of it is giving the ultimate consumer (the shooter that buys it and uses it) a new adventure/perspective and hopefully some enjoyment that he doesn't get out of something he already owns. Why did I just buy a 30-06 rifle when I already have: a .308 M-16, a sweet .308 Remington 600, a 30-06 JDJ Encore, a .300 Win. Mag, and ...?
We are surely blessed!
As I and others have said: JD Jones, by developing his cartridges, put handgun hunting into the limelight and the modern ages and ...etc. Basically the total positive long term impact of what he did for handgun hunting with his JDJ's can not really be summed up in in simple words, IMO.
Besides that, it gives you something to spend your money on other than whiskey, fast horses, and faster women!
Not to mention it is just plain d--- fun.
