JDJ cartridges????

IAM Rand · May 8, 2023

Any one reloading for the JDJ stuff. specifically the 309 and the 375. I have seen a couple of Thompson Center guns in those calibers.

I am mildly interested in them but, cannot find a good source for brass. I know that I can use the 444 Marlin but, don't feel like having to form the cases. Not only that but, 444 isn't super plentiful and it is also expensive.

Just pondering.

Ivan the Butcher · May 8, 2023

I have never seen already formed 375 JDJ Brass!

I took a Super 14" Contender barrel in 44 Mag and lengthened the chamber to 445 Super Mag and Nag-na-port ed it. I Throw 300 grain slugs over 26.6 of WW296. Super Blackhawks tremble at the thought!

Ivan

venomballistics · May 8, 2023

Forming cases is going to be your life at this stage in the game.
In the 32-20 thread, its the same deal you'll face, only that's a far better established cartridge than anything JDJ.

tt66 · May 8, 2023

I had a 6mm JDJ #2 for a while and I loved the performance, but I hated the process. That round is based off the 225 Winchester and brass for that is very hard to come by as well

Tim

6string · May 8, 2023

The JDJ cartridges are very good for what they are, and for the intended arm they were designed. They are also a remarkable sign of the times! There was a lot more interest in reloading, and not just from the standpoint of cranking out buckets full of 9mm in front of a progressive press.
Nothing in this class of cartridges was ever intended for high volume shooting. So case forming, trimming, annealing, and all the rest, isn't such a big deal. In fact, it's a good part of the fun.

If you got ahold of 40-50 pieces of brass, you'd be all set for some time.
Just keep your eye out for a package deal: gun (or just the barrel), dies, and some brass.

But, everyone's point about component availability is well taken.
The last time there was a protracted shortage like this, we were fighting the Germans in Europe and the Japanese in the Pacific.
Something to think about....

dwh · May 8, 2023

I’ve always wanted to convert a marlin 444 to 309JD. Even more so now that the flex tip bullets are available. Maybe it is viable maybe it isn’t. I’ll never know I have to many projects now.

Skeet 028 · May 8, 2023

I had a 309 many years ago. got the whole thing as a package. Wasn't a bad round...someone wanted it more than me. I've never really found 444 hard to find. Annealing is a bit of a pain. A good handgun hunting round

IAM Rand · May 8, 2023

Local auction has both a 309 and a 375 JDJ. Not going for a whole lot right now but, not sure that I want that kind of a project. GB has 444 brass but, between getting the dies and the brass and all of that, just don't think it is a project for me.

Ivan the Butcher · Mar 13, 2025

444 Marlin was originally formed from 303 British or 30-40 Gov't cases. Why not fire form the JDJ rounds from them? Should make the 309 JDJ very easy! The 375 should be fairly easy too.

Ivan

rays44 · Mar 24, 2025

IAM Rand said:
Any one reloading for the JDJ stuff. specifically the 309 and the 375. I have seen a couple of Thompson Center guns in those calibers.

I am mildly interested in them but, cannot find a good source for brass. I know that I can use the 444 Marlin but, don't feel like having to form the cases. Not only that but, 444 isn't super plentiful and it is also expensive.

Just pondering.

I reloaded and hunted with a number of the JDJ cartridges in the "80's and 90's, including the .375. The .375 was not difficult, but the nature of the cartridge requires fire forming .444 brass. If you don't want to go through the trouble, then the cartridge is not for you.

JDJ cartridges????

IAM Rand

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Ivan the Butcher

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venomballistics

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tt66

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6string

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dwh

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Skeet 028

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IAM Rand

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Ivan the Butcher

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rays44

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