Wanted some tips on fireforming loads, and ballistics? Also wondering what bullets have worked best for you? Prospective new projects.
Thanks! e-mail at drminak@hotmail.com

HHI 812
I recently built a 25 Souper for Wayne van Zwoll. He tested several loads, they should see print soon.
Charlie

I've just finished my 338-06 AI (built on a mauser 98). I'm currently working up loads and fireforming using Varget and the 200 gr Hornady bullet.

I use either 35 Whelen brass or 30-06 brass run thru my 35 Whelen die as the starting point. This too-large brass is then run into my 338-06 AI die just far enough to shrink the neck so that it will chamber - leaving a false shoulder for fireforming. It's the only way to properly match the cartridge to the headspace I have found (the hard way).

I use 55 gr of Varget to fireform, with the bullet seated normally to fit the magazine. Accuracy of the fireforming load is pretty good. I have not chrono'd it yet. I plan to move to the 210 Partition as soon as I get the load close enough to justify the more expensive bullets. maxman

Charlie-how long ago was this? Just curious how long I might have to wait. Is this .25 Souper or .25 Super? I've seen both names used, or are they just two different chamberings? What kind of ballistics have you gotten in this conversion?
Maxman-So your sizing die can neck down the .35 Whelen brass in one step? Just concerned if I use .270 or .30-06 brass and size up, I won't have a false shoulder and wondering what kind of problems you ran into? What if I seat my bullet long into the rifling, since I have a single shot? How do you like the cartridge?

HHI812
He has had it for about 3 months now. I would guess in another 3 months or so the print should be out. But you can never tell what the editor will do.....
Charlie

I have had a 25 Souper for a number of years. I size up 243 cases. I am using IMR-4350 and Sierra 120gr BTHP Gamekings. At lunch so don't have the numbers. My rifle has a 20" barrel, use it with climbing tree stands.Rick.

HHI - yup. Here is my process starting with 35 Whelen brass:
- lube the outside of the neck lightly
- run it into the 338-06 AI die just far enough to allow the case to chamber with a slight crush. Once this distance is set, lock the die and leave it there.
- process all the cases and then load 'em up.
35 Whelen brass is a special order deal where I live so, I will be using 30-06 brass from now on. Now that I have 35 Whelen dies, it is easy.

If I start with 30-06 brass, I will size it up first using the 35 Whelen die (lube the inside of the neck real good here). I sometimes will run it into the 338 die expander first, and then expand again to .358 in the Whelen die to make it easier on the brass. Not sure if it's needed, but that's me...

I tried just taking 30-06 brass and running it into the 338-06 AI dies, loading it up and leaving the bullet seated long. Single-loading the rounds into my rifle for forming. I got mild to severe case head stretch (impending head separation) and flattened primers in every piece of that bag of new brass. I only seated the bullets maybe 1/4" into the case and then let the closing of the bolt jam the bullet into the rifling and back into the neck of the case. It should have held everything nice and tight - but did not. There was no consistency of behavior - I can only attribute this to the varying neck tension of each individual piece of brass.

Near as I can tell, the force of the striker still pushed the case forward over the base of the bullet and then ignited the powder. So, I got the brass to flow right at the head of the brass rather then at the shoulder. At least it was only a $13 experiment (read 'loss').

If you give the case a false shoulder to headspace off of, the brass will push outward at the correct place. No need to depend on neck tension for headspace control - just not good enough I found. You can seat bullets normally and actually do some preliminarry accuracy testing etc when loaded like this. Your rifle may have a weaker firing pin spring than mine, so you might not see these problems, however. I also wanted to go with the bullets seated into the lands initially, as it would make less work and $ for me to fireform these cases.

So far, I love it! It's a real hoot to shoot and sure hits hard. Hopefully, I will have some hunting results to share in the next few months. But for now, it's looking real promising. I'm glad I went this route - I'm sure you will be too! maxman

Well...something I can finally write about: I've been shooting the 338-06 Ackley since the late 80's and find that necking 35 Whelan works best for me. As others have posted, short-sizing the 35 caliber neck allows for the most positive head space during fire-forming with the fewest steps. I use Remington brass (obviously), 64.0 grains of Reloader 19, Fed 215M primer and the 200 grain Nosler BT for most things here in Texas. I suppose if money is no object you can just fire form 338 A-Square. My Sauer 200 has a very long magazine so I can seat way out but the load is still very compressed. The reinforced shank on the 338 bullet seems to cause less meat trauma than other calibers of BTs I have used. My barrel is 25.5 inches and I chronograph 2850 to 2880 at summer temps. Some recent published data indicated 67 grains of R-19 but I don't know how the hell they got it in the case.

I don't have a 25 Souper but do have a 257DGR (http://www.duanesguns.com) which is very similar to the 25 Souper.
The 257DGR pushes the 243 (or 260) neck shoulder juction back to make the shoulder 30 degrees and removes a bit of body taper.

I get 3700+fps with 70gr bullet and 3200+fps with 100gr bullets.

The load I have settled on for deer and antelope uses a 100gr Nosler BT @ 3150fps. I can go faster but this is the most accurate with this bullet.

Good Hunting
Jeff in ND

I too have a .257 DGR---on a Kimber 84 action. I have not yet shot it, but I like the fact that there is very little fire-forming required to expand the case to its final dimension. I have resized some Lake City National Match .308 brass on the assumption that it is the strongest parent brass available and might give a little more velocity. +3000 fps with a 115 grain bullet would be nice, but we shall see. There's nothing wrong with 100 grain bullets either, especially for deer I am told. My rifle was built by Greg Tannel using a Lothar Walther barrel. The barrel is only 20.5" long, which was deliberate. I like light, short rifles.

Jordan

Hey guys, forget all this brass reforming, necking up, necking down, etc for 338-06. Buy all the brass you need from Norma. They headstamp it 336-06 A-Square.

Whats the Norma .338-06 brass run per 20 or per 100??

FN in MT

Frank;I just bought some Weatherby brass from Cabelas it is made by Norma $18.99 for 20 $89.99 for 100.w/regards

FWIW I fire form my brass for a 257AI & 7x57AI using the std 257 Roberts and 7x57 Mauser data. I'll experiment with different powders and when I find something promising I'll go from there.