JDJ cartridges

Are these cartridges avaiable with the “correct” headstamp or with the one of the case they were formed from only?


I have .300 JDJ which has it’s “parent” Headstamp (R-P 444 MARLIN)and .338-06 JDJ, .358 JDJ and .375 JDJ which all have a Qualcart JDJ headstamps

Yes,there is qual cart that makes a lot of wildcat cases and loads custom cartridges but apparently there is no JDJ cartridge with " JDJ 375 JDJ" or similar headstamp,altough considered more propietary cartridges than wildcat ones


Proprietary vs. Wildcat has always been a gray area for collectors and Qual Cart (and others) has only made it more so. That’s one of the reasons I cater toward the old original wildcat cartridges from the golden age (1930s to 1950s).

To me, the J D Jones’ cartridges are all wildcats. I personally think that “proprietary” is an outdated classification. Reamer makers will grind to any spec that the customer may want although most will not mark the reamer with a “proprietary” name, mostly as a courtesy to the designer. Unless the designer copyrights or patents his brainstorm, there is nothing to prevent anyone from using the original name on either the reamer, cartridge case, or barrel.

I know this has strayed from your original question. There are several cartridges with a “JDJ” headstamp but whether or not the 375 is one of them I cannot say.



Hornady made factory ammo for Thompson/Center for the .375 JDJ. The headstamp is

T/C 375 JDJ