Picked up a barrel on Gunbroker.com that came with dies and brass. Do any of you have experience with this cartridge that you'd be willing to pass along. I contacted SSK for load data, but it is kind of limited with powder selection. This cartridge appears to be a twin to the 7mm Super Bower, but I can't confirm it. Any insight would be appreciated.

Thanks!

Congrats on the new caliber & fine Barrel.
You will have a wider variety of good bullets now . (than 10 yrs.ago)
Myself , just having a TC/Contender in 7mm. TCU , I have been advised that loadings with all copper( Barnes & Cutting Edge) should be double checked for powder weight ...& approached with caution.
Good Luck.

LOOKED BUT COULD NOT FIND WHAT CASE THE 7mm JDJ#2 IS BASED ON. I ASSUME IT IS NOT THE 225 WIN CASE, SO WHAT IS IT BASED ON?

LOOKED BUT COULD NOT FIND WHAT CASE THE 7mm JDJ#2 IS BASED ON. I ASSUME IT IS NOT THE 225 WIN CASE, SO WHAT IS IT BASED ON?

LOOKED AGAIN AND LOOKS LIKE IT IS BASED ON THE 307 WIN CASE, A LOT OF CASE FOR A CONTENDER.

Finally got around to determining the case capacity of the fireformed brass, and found it holds 51 grains of water. My Powley Computer equates that to 44 grains of powder. It also suggests using IMR 4064 powder with 110 and 120 grain bullets, IMR 4320 with 130 and 140 grain bullets, and something between IMR 4320 and IMR 4350 for 150 grain bullets. The Powley Computer is set up to make it's calculations on an average of 45K psi. This may be on the upper end of allowable pressure for a Contender, but the pressures can be lowered by using slower burning powders than the ones recommended. The calculated velocities are as follows: 110gr 2750fps, 120gr 2650fps, 130gr 2550fps, 140gr 2450fps, 150gr 2350fps. Unfortunately the throat is very long and precludes the use of the 110 and 120 grain bullets, as there would not be enough, or any, of the bullet in the case if you wanted to get them close to the rifling. That is just as well, since I was planning on using 140 or 150 grain bullets in this barrel anyway. Only through careful load development will I be able to see if these velocities are attainable without excessive pressures. The 7mm Super Bower data that I was able to find does closely resemble my calculations in powder charge and velocity, and it exceeds the data provided by SSK for the 7mm JDJ #2, in some instances. Looks like I got work to do.

ONE BIG THING THE 6.5 JDJ HAS GOING FOR IT IS THAT A LOT OF 6.5 BULLETS ARE MADE TO EXPAND AND WORK AT LOWER VELOCITIES. THERE MAY BE A LOT OF 7MM BULLETS OUT THERE THAT ARE MEANT FOR MAGNUMS AND MAY NOT EXPAND AT HANDGUN VELOCITIES. CHOOSE YOUR BULLETS WELL. BOUND TO BE SOME GUYS OUT THERE THAT CAN RECOMMEND 7MM BULLETS FOR HANDGUN LOADS.

Bullets are not a problem for the 7 mmJDJ #2....Sierra, Hawk, Woodleigh, and Fury....any that can be used in the Waters or STE will be great

I've never quite managed to keep track of all the JDJ cartridges.

In a Contender with limited loading data, I would work up my loads carefully. Working with powders not listed in JD's load data I would calculate what heavy bullet load should go around 2,000 fps and start working from that point on up.

It would have been handy if it had not been throated so deep. If I were working with it, I would have liked to work with bullets 130 and under in it. You may have more of a challenge working with heavier bullets for medium game.

By the way good find. A 7mm X 307Win should be a good chambering to work with. If you determine it to be a keeper, you might want to round up more brass when you can find it. I believe my local reloading shop has a bag or two last time I looked through his brass selection.

Bob R

Ran some initial tests using Nosler 140 grain BT's with W760 powder, and Fed 215 primers. Shooting was done at 100 yards with 5 shot groups. I tested 40.5 grains to 44.5 grains with 42.0 and 44.0 grains giving the best groups, .617 and .974 respectively. I had forgotten my chronograph, so the following week I went back and tested the two loads. Velocity for the 42.0 grain load registered 2268 fps, and the 44.0 grain load went 2373 fps. I never experienced any stiff or sticky extraction or opening of the action, so I'm going to try Varget which has a little faster burn rate, and is very close to IMR4320, which is what the Powley Computer recommended. The previous owner of the barrel stated that he used IMR4350 with success, but I don't have any, and I don't care for the "twig" length extruded powders. If I can get 2400 to 2450 fps with the Nosler 140 grain, I'll be happy.

I'm also curious, what is the parent case for this round. I have a 6JDJ and 6.5 JDJ on the 225 case.

Mike

The parent case is a 307 Winchester. Think 308 Win with a rim.

45MAN,
WHY DO YOU USE CAP-LOCK ON EVERY POST??

RELOADER28: IT IS AN OLD HABIT FROM MY ARMY DAYS WHEN I TYPED ON A MILL (AN ALL CAPS TYPEWRITER), PLUS IT IS EASIER TO TYPE THAT WAY, AND I CAN READ BIGGER LETTERS BETTER.

I have a 7mm JDJ#2. Try 140 gr. Nosler Ballistic tip with 43.0 gr. IMR-4350, with Fed. 210 primer.

I too have joined the ranks of shooting the 7mm JDJ #2 in the contender and Mech8's original question: This cartridge appears to be a twin to the 7mm Super Bower, but I can't confirm it. has not yet been addressed in this thread.
My barrel was obtained from a NY shooter and it was recommended that I use 7-08 Ackley dies to form my brass. Reloading for this cartridge uses starting loads suggested for the 7-08, utilizing slow burning powders.
Trimmed 444 marlin brass is used as the countersink in the barrel accomodates it. Dies have been procurred and have proven to be perfect for this barrels chamber. I hope that I've shed some light.

I might add that the case to the right has not yet been fireformed, at which time a Ackley 40 degree shoulder will be imparted.
The cartridge may also be referred to as a 7x307AI.

Thanks, rleprechaun
I'll try that load!