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.

I am somewhat surprised by how?upset some of you guys seem to get over really very mild criticisms of JDJ cartridges. In no way do I mean to offend.?I?don't really have a problem with JDJ cartridges at all; people can?do and buy?what they want so far as I am concerned, but?I remain completely unimpressed by them and unconvinced of their merit, and I offer my explanations as to why to not defend myself so much as to help you understand my personal perspective. Perhaps you could explain to me why you find them so worthwhile (though I don't find "magic" particularly compelling).
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The prevailing?argument seems to be that JDJ cartridges are "better" because they bring the Contender platform to the limit of performance. This is debatable, but I'll allow if for now for the sake of argument. I think it is?worth pointing out that?some?JDJs may have?exceeded the?chronic?performance limit of the first Gen Contender, but?I don't really see the merit in pushing it anyway.?My thinking is that if?one feels the need for?"MORE" then get an Encore which is available in so many common, powerful cartridges, and has been for 20+ years now.?If one prefers the smaller platform, easy portability, and pleasant shooting characteristics of the Contender or G2, then why spoil the fun with?chamberings that operate at the very edge of that platform and undermine some of?those characteristics? If less powerful and exotic?cartridges get the job done with less boom, blast, powder, and stress on the action and?one's hand, then they are better to my thinking, as they are more easily obtained, pleasant, and neighborly.
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Regarding neighborliness, the particular incident I recall is some guy blasting away with his 375 JDJ Contender at a public range in Indiana (there's nothing bigger than Whitetails in Indiana, but let's?suppose this guy is the unlikely Hoosier that travels out-of-state to hunt big game).?I am sure his huge earmuffs (likely with plugs?beneath)?and?standing behind the muzzle?made it tolerable...FOR HIM (wonder what he's going to do in the woods though).?What was irritating to me was the?deafening shockwave that emanated laterally from the muzzle, especially for those of us who find regular inside-the-ear hearing protection adequate. Fortunately, his poor shooting (perhaps due to recoil-induced flinch) irritated him enough that?he moved down the line (away from me at the 100 yard line)?to 50 yards and then to 25 before he eventually called it a day. I think that if this had been a 357 Magnum, 44 Magnum, or even something like 357 Herrett this wouldn't have been the dreary, deafening?spectacle that it was, and all of those cartridges would have done the job on Whitetails or steel rams.
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Also, I am not really sure what?anyone is trying to say about 444 being easy to find. It IS NOT and NEVER WILL BE anywhere near as common, cheap, or available as 30-30, 357 Mag, 44 Mag, etc. I get 30-30 cases for free or for commodity brass price picking?through range brass?all the time. I have yet to find a single?444 Marlin?case in literally thousands and thousands?of rounds I have scrounged through over?the last?7 years I've been doing this. Sure I can buy 444 Marlin brass when it's available (it is a seasonal run affair, or was), but it costs about 100x more than a 30-30 case. And even if I were to buy NEW 30-30 brass it costs about half to one third as much as 444.
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The other reason I don't get excited about JDJs is their internal ballistic properties are?the reverse for what is desirable in a?handgun (they?are NECKED DOWN versions of the parent cartridge). Handguns, with short barrels,?use fast burning powders so it doesn't?just become wasted fire and boom out the muzzle. Fast burning powders run up against?chamber pressure limitations and?need large bullet diameters to increase the surface area that chamber pressure is applied to. The greatest muzzle energies for a given amount of propellant?are achieved with straight-walled or nearly straight-walled cases, therefore. Necking down makes sense in a rifle because not only are rifles very strong?and can handle high chamber pressures, they have long barrels that can make use of slow burning propellants, and they have great ergonomic stability, allowing one to actually make use of the superior external ballistic properties offered by smaller bore sizes.?That is why I said it makes more?sense for 375 JDJ to be in a Marlin lever-action rifle, while 444 Marlin makes more sense in a Contender pistol. And that is why to me 357 Herrett makes sense as a Wildcat for a handgun.?It is a NECKED UP version of a?rifle round. The conversion makes the case MORE EFFECIENT for the platform, not LESS EFFECIENT. It improves performance?over its parent case?rather than reduce it.
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I am not sure what anyone is trying to prove with saying that JDJs were?the only thing available "back in the day."?Wasn't 45-70?one of the original chamberings for the Contender? Is there a?game animal?in North America that?requires more than what 45-70 can deliver? 357 Herrett, which predates the JDJ as well,?is straightforward to convert from 30-30, and if you necksize or minimally size, so far, my 357 Herrett brass?seems to be immortal (I haven't worn one out yet). It is pleasant to shoot, even with max loads pushing 200 grainers, not terribly loud, and I am?confident it is far more effective on Whitetails than ANY 6.5mm mm cartridge out of a short barrel under 200 yards. I've shot and butchered enough deer to know what works well, killing them quickly?but with?minimum meat damage.
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If one is convinced that one needs a small bore handgun cartridge, the 7-30s Waters is out there, and has been since what...1974...3 years before the JDJs? If you want a really small bore, the 223, 22 Hornet/K-Hornet, 219 Donaldson Wasp, and many other cartridges have been around for far LONGER than the Contender, let alone JDJs.
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It just dawned on me that J. D. Jones pretty much did the reverse of the JDJ series?with the Whisper Cartridges. He took good rifle cartridges and necked them UP to slow them down to handgun velocities, largely negating the benefits of flat trajectories, etc. This was done to make them subsonic and quiet, which I suppose is worthwhile for some people. Why not just load pistol cartridges like 9mm and 357 Mag or whatever with extremely heavy bullets? To my mind J. D. Jones is perhaps the most overrated, if prolific,?Wildcatter. Not saying this is bad, because any Wildcatter at least adds to the repository of reloading knowledge, but I'd rank him behind every other Wildcatter I know of.
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