7-30 JDJ Case Forming.

[Darklin]

I just got a 7-30 JDJ and the barrel is stamped 7-30 Waters but the 7-30 JDJ is on the lug. I have found the dimensions in the Cartridge Conversion book, but the barrel actually has room for the case to have a neck that is 1/4 inch long but the Case neck for the 7-30 JDJ is only .188. All the cases I got with the barrel have a .250 neck from the shoulder but the barrel has even more room for the neck. All the bullets I have just barely sit in the case and still only barely touch the rifling. Any suggestions or is this a re chambered barrel??

[Mk42gunner]

My guess is a rechambered barrel. Nothing necessarily wrong with that, as long as the work was done well. Doesn't sound like it totally matches with 7-30 JDJ dimensions, so welcome to wildcatting.

Since 7-30 Waters brass isn't all that common, I would start with new 30-30 brass and neck it down enough to chamber, then fireform to fit your chamber. After that, work up loads carefully.

Robert

[Harter66]

I'm with Mk 42 .

[Darklin]

My guess is a rechambered barrel. Nothing necessarily wrong with that, as long as the work was done well. Doesn't sound like it totally matches with 7-30 JDJ dimensions, so welcome to wildcatting.

Since 7-30 Waters brass isn't all that common, I would start with new 30-30 brass and neck it down enough to chamber, then fireform to fit your chamber. After that, work up loads carefully.

Robert

In your opinion would it be safe to use regular 7-30 Waters Loads as the starting point for load data. Case compacity is higher than the regular 7-30 just the Neck seems to be way longer.

[Mk42gunner]

I would use loads for the 7-30 Waters as a guide, comparing case capacity. I don't believe I would start with top end loads, it is called working up a load for a reason.

When I was messing with a 6mmx300WSM; I did a lot of comparing of similar case/different bore, and same bore/ different case capacity. I didn't blow anything up, but I am not the one to push for every last foot per second either.

Good Luck, be safe, and do your research.

Robert

[tctender]

I would use 7x30 data for starting loads. You should be able to up some just watch for pressure and that starts back down .

[Darklin]

It is confirmed. The barrel was re chambered by SSK to the 7-30 JDJ. Had good luck and decent accuracy from the 7-30 Waters Loads. Now just to get some new 30-30 brass and start making some more. Thanks everyone for the help.

[Rapier]

I do believe the 30 JDJ is based on the 444 Marlin. That might be where your case length went to, unless JD did the same thing he did with he 6.5 JDJ and based it on the 225 Win Mag. The 225 is a 65k case (rimmed 220 Swift). JD did shoot hot loads in the 30-30 years before the JDJ line came out. With the JDJ line he went to tougher cases.