Forming brass

Johnn Peterson

Johnn Peterson

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Looking for a little input/guidance and experience/expertise. Using forming and trim dies, I've formed brass down in caliber size, ie: 219 Donaldson Wasp from 30-30. I've never had the opportunity to go the other way, up in caliber size. I've recently purchased a 358 Norma Magnum and while I presently have a supply of brass I was wondering is there was any specific or required procedure to form 358 NM brass from 338 WM? Anything special to go up that additional 0.020" or would it be possible/advisable to just run it through a 358 NM resizing & decapping die?
 
The Trim-To-Lenght for the 358 NM is 2.498" so there is no real problem using the .338 WM.

But you will have to fireform, because the distance base / shoulder of the .338 WM is 0.048" shorter compared to the .358 NM.

I prefer using .300 WM as a base cartridge for the .358 NM.
 
I can't speak to the specifics of going from 338 to 358 on the magnum case but I've done a pile of .30-06 to .35 Whelen. It's a simple matter of running the 06 case in and pulling a Whelen case out. There's no fire-forming required.

A tapered expander is needed but my RCBS .35 Whelen die came with one so no issues there. I don't know if you'll need one.
 
Thanks guys. I appreciate the input and suggestions. In my reloading room, while fumbling through some of the equipment and tools I have, I came up with a 'possible' plan. One of the calibers I have is the 348 WCF. I was thinking, if, I 1st ran the spent 338 WM cases through the 348 resize die, just enough to run the neck through/past the expander plug, and then normally run it through the 358 NM resizing die and expander plug, with the required lube, that should only mean jumps of 0.010". What do you think??
 
Johnn Peterson said:
Thanks guys. I appreciate the input and suggestions. In my reloading room, while fumbling through some of the equipment and tools I have, I came up with a 'possible' plan. One of the calibers I have is the 348 WCF. I was thinking, if, I 1st ran the spent 338 WM cases through the 348 resize die, just enough to run the neck through/past the expander plug, and then normally run it through the 358 NM resizing die and expander plug, with the required lube, that should only mean jumps of 0.010". What do you think??
Click to expand...

Might not be a bad way to go. Could maybe swap the 348 expander into the 358 die for the first step and then put back the 358 for the final step.

Do you aneal your cases? Makes forming easier and you should get fewer split necks.
 
All of the methods spoken about here will work to neck up the brass. Necking up to 348 first might be worth a try, although I have never had a problem going all the way in one stroke, especially using a tapered expander ball.

RR is right about not having to worry about headspace, and Mauser98 about no need to fireform. I used full power loads in reformed 338 brass for both range work and hunting. The brass was fully fireformed with the first shot and point of impact exactly the same as with fireformed brass.

Used 300 Win brass a few times, but it is a bit more work to shorten the necks, and sometimes they needed to be reamed because the lower part of the neck was formed from the shoulder area of the 300 case and ended up too thick to chamber a loaded round.

It is a great cartridge, and I have loaded for the Nine Norma since I got my first Husqvarna in 1969. Have used everything from 7mm rem Mag to Norma unformed basic magnum brass. The 338 Win Mag is by far the easiest to use. :)

Ted
 
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