309 JDJ

[Tad Houston]

What do the 309 JDJ ballistics compare to? Is this a contender chambering formed from the 444 brass? I have a factory 14" 30-30 barrel that may be a good candidate for a rechamber. Thanks for your replies- Tad

[Del]

Yes, the .309 JDJ is based on the .444 marlin case.  IF I remember right, it is comparable to the .308 Win. from the encore 15" barrel.  I read an article when the encore first came out, and JD Jones did some testing with the .308 Win. & .30-06 in 15" barrels, I believe the .309 JDJ was almost identical to the .308 or very close on it's heels.  I hope this helps, and if I'm off a bit on my information, hope someone steps in to set things straight!

Have you thought about the .30-30 Ackley Improved!?
125 - 130 grn bullets @ 2500 fps
150 grn bullets @ 2400 fps
Not bad from a 14" barrel!

Good luck with your choice!
Del

[kenacp]

I have  and love my 309JDJ(very accurate), but would look at the30-30AI,less trouble with brass I would think.

[KYODE]

i know the 309JDJ would be an excellent round, BUT i do really, really like my 30-30Ackley Improved factory 14"er.
a 309JDJ rechamber may remove the factory throat on that 30-30 barrel, if that is beneficial to ya. i personaly,  havn't had any trouble getting what i wanted out of a factory throated barrel as of yet. :?

if ya want to read a little on the 30-30AI, and see a colection of data from a few different barrels, from custom to factory, larry sand has an article on it at www.handgunhunt.com

[Tad Houston]

I take it from all the posts on the 30-30 AI, it must be ballistically close to the 309JDJ? I almost bought one when they where on sale at midway for $199. Just curious, what kinda velocity can i get from a 14" 309JDJ w/150 gr Nos. BT? Thanks- Tad

[Phil Magistro]

I have some old 309 JDJ loading info from SSK that show 46.0 grains of AA2520 push a 150 BT at 2414fps.  Doc Rogers has written many times about this load and it's accuracy.  I've used this load a lot and like it.  The only problem I've encountered is split necks in over 30% of my casings, even with lower power loads.

Phil

[Kivaari]

Are you forming your own cases from .444 Marlin?

Are you annealing the brass....?

[TNrifleman]

Your 30-30 barrel is an excellent candidate for rechambering to 309 JDJ. In fact, my SSK 309 barrel was a T/C 30-30 barrel converted by SSK. The 309 is a great handgun cartridge. Brass is not difficult to form from NEW 444 cases if instructions from SSK are carefully followed.

[Lone Star]

The .309JDJ is a fine cartridge, but it is well behind the .308WCF in power.  Nolser data shows 2712 fps for a 14" .308, while the 2400+ fps with the same bullet is a classic JDJ load.

That said, a 150-grain bullet at 2400 fps is a wonderful load.  I've shot dozens of Kodiak Island deer with my .300 Savage, firing a 150 BTip at 2350+ fps, and it kills very very well.  Trajectory is plenty for 200 yard shots if you want to take them, and bullet performance at 250 is great with almost full stem-to-stern penetration.

The .30-30 AI is a good cartridge, but it must operate at higher pressures to come close to the .309.  And contrary to legend, this cartridge shape does not reduce case head thrust on the breech once pressures get high (50,000+ cup).  Ackley never used pressure equipment to test his theory, nor did he do the simple engineering calculations to prove it doesn't work - he was interested in selling the idea afterall.  Even some basic intuative thought on the subject shows the theory's flaws.  But that does nothing to take away the fine overall performence of the AI cartridges, it's no wonder they are still popular over 40 years after they were originated.

[Graybeard]

I take it from all the posts on the 30-30 AI, it must be ballistically close to the 309JDJ?

No, actually it's not. There is a large difference in the case capacity of these two rounds. The ONLY way you can come even close to same velocity is to run pressures in the .30-30 AI way above safe levels.

The .309JDJ is a fine cartridge, but it is well behind the .308WCF in power. Nolser data shows 2712 fps for a 14" .308, while the 2400+ fps with the same bullet is a classic JDJ load.

The .309 JDJ has a definite case capacity edge on the .308 Win. In handguns max loads of each are quite close. Way closer in the real world than the 300 fps difference shown in your example. I'm going on memory here and that often is faulty but I believe SSK supplied data shows 2400 fps for the 165 in the JDJ. That's the bullet weight JD recommends for this round. More specifically the 165 Nosler BT. Real world difference should be more on the order of 100 fps in favor of the .308 Win. I think. An edge yes but a slight one.

Hornady which shows data for the .309 JDJ lists two loads that develop 2500 fps for the 150 grain bullets and two loads that develop 2400 fps for the 165s. They don't show data for the .308 in handguns but they do for the very similar 7-08 and for it they run 154s only 2400 fps. In a 22" rifle barrel they max out the 150 at 2800 fps and the 165 at 2600 fps.

So as you can see when looking at data from the same source for both the numbers are much closer than taking a load for one from one source and a single load for each from difference sources. In real world use you'll get pretty much equal performance from a .309 JDJ in a Contender as you'll get from the .308 Win. in an Encore or other single shot. Not quite equal perhaps but close enough there is no real advantage for one over the other. One hundred fps is meaningless in on game performance. Even 200 fps is on no signifcance inside 250-300 yards where 90%+ of shots are taken on game.

Looking at the Nosler data there is one load showing 2730 fps for a 150 grain using IMR4064. Looking over the rest of the data one sees one load maxed out at 2629 fps, one at 2563, one at 2540 and one at 2497. With the favored 165 grain bullets you see loads maxing at: 2342 fps to 2484 fps or in other words within 100 fps of the .309 JDJ normal loads.

For Contender shooters the .309 JDJ is the .30 caliber top dog. For Encore and bolt gun shooters there are much hotter available if you feel the need for speed.

[Lone Star]

You're correct - I think - I may have miss-remembered the 2400 fps load, which is SSK's current published velocity for 165 grain bullets, not 150s.  However, JD is quoted in the Accurate #2 Manual as saying that the 165-grain BTip does "about 2200 fps" - a rather odd discrepancy, but this also happens to be the velocity that JD always mentioned in my old issues of the Sixgunner, JD's monthly publication.  Which velocity do we believe?  Looking further at .308WCF data:

Nosler 165 @ 2475 fps
Sierra 165 @ 2500 fps
Lyman 165 @ 2484 fps
Hodgdon 165 @ 2580 fps

This puts an average max velocity for the .308 WCF at 2510 fps, 310 fps ahead of JD's "quoted" velocity - or 110 fps ahead of what his sales material says (along with some reloading manual data).  None of which changes what I said in my last post - a 150gr at 2400 fps is a wonderful deer load.  (165s are, in my rather extensive experience at this velocity, not required on deer.)

PS - experienced handloaders are aware that the same case gives greater bullet velocitiy as bore diameter increases.  This is because with the same chamber pressure the larger bullet base area allows more propellant energy to be transfered to the bullet. giving it more energy.  A very good example is the Hodgdon pressure data for .308-based cartridges, where the muzzle energies for the .243 through the .358 range from 2000 fpe to 3060 fpe - same case capacity, different bullet diameters.  Using Hodgdon data with the same bullet weight for both the 7-08 and the .308:

7-08 - 150 @ 2823 fps = 2655 fpe
.308 - 150 @ 2937 fps = 2874 fpe

So for rifle data, the .308 produces 219 fps more velocity than the 7-08 does at equal pressures and barrel lengths - and from the same data source.  Both Lyman and Accurate data shows the same trend but with varying magnitudes.  Yes, the 7-08 is similar to the .308, but obviously its muzzle performance is not.

Note that none of this is meant to be disrespectful of Graybeard's post - I respect the heck out of him and greatly appreciate his insights and this forum -  but I went into this detail to try to enlighten members and to try to improve their technical knowledge.  BTW I'm still learning too and am hardly infallible.....

[Jay HHI6818]

I worked up a load in my 309JDJ last year with the 165 gr Nosler and N160 powder. 2325 FPS out of a 14 inch barrel and I'm still not a the MAX. I was going to try for 2400 but never got around to it. Maybe next year???

[Phil Magistro]

Are you forming your own cases from .444 Marlin?

Are you annealing the brass....?

1.  Yes
2.  No.