256 WIN MAG case forming question

[ciphery]

I know the parent case is a 357MAG but am looking for input from those that have necked down the parent case vs resized the 256 its self. I want to know how many steps to get from 357 to 256 and also the success rate.

 

[smellie]

I have no idea at all about the .256 Mag except for what you have already stated: the parent case is the .357 Maggie.

That said, I make keychains out of .38 Special and .357 Magnum brass (having no use for the stuff: I shoot the old .38S&W in my Webley, Enfields and Smith).

I can go from a fired .38 Special or .357 to .30" calibre in a single step, using a 7.63 Mauser pistol die, with 100% success rate: zero failures.

And I can go from a .30 down to a .22 in one step (.30 Carbine to .218 Rimless), again with zero failures, this all on once-fired brass.

I would think that if you were to go from .357 to .30, then down to your .25 in a second stage, you should have good results.

Hope this helps a bit.

 

[woodchopper]

you need 2 steps minimum.

neck down to around 7mm then again to .256

I tried doing it in one step and it won't work, even 2 steps is not always going to work and you lose a few cases.

 

[Al-Sway]

As with many of these radical case changes, you are best off with new brass. I always size it in the parent case die first (in this case .357) to ensure roundess. If there is any irregularity at the start you will get a wrinkle.
I also remove the decapping rod when necking down. I don't know why, but it improves the success ration. Once fully sized you can run the expander button through.

 

[vagrantviking]

Depending on how hard or worked the brass is that you are using it might be worth annealling them before you start.

 

[ciphery]

I am actually using once fired 357mag and taking it to .224 as a 256 wildcat of sorts.
I want all the info I can get before commencing building dies,reamers etc.