I just bought a 35 whelen and a box of shells (nickel). A friend offered me some of his nickel 280 brass and told me I could neck it up with any 35 whelen full length resizing die. I have not bought dies yet and am considering Redding. Question: Will the 280 brass work without special dies?

You might go the other way, but I certainly wouldn't try going from .284 I.D. to .358 I.D., especially not with nickel cases. First, it would require a tapered expander (or a set of tapered expanders). If you just try to run a conventional .358 expander ball into a .280 case, the case mouth will likely collapse.

Other than that, expanding a neck that much could result in a split, and will certainly result in uneven neck walls which are much thinner than your standard .35 Whelen walls.

The shoulder on the .280 would have to be pushed back a bit (no big deal), and the .280 cases would likely need trimming.

All in all, I don't think such a case conversion wise.

Thanks for the explanation. You saved me alot of time and fustration. Anyone know of a source for nickel 35 whelen brass?

I have never liked nickel (plated) brass in bottle-neck rifle cases for reloading...they just don't stand up to repeated reloading and you can't anneal them.

I haven't found nickel as difficult to work with as some people, but on the other hand, it's doesn't offer much advantage either.

If you want to reload those factory .35 Whelen's, you probably won't have any trouble.

My RCBS dies came with a tapered expander so that isn't a problem for me.
So necking up .280 brass is possible. If the brass splits on opening up the neck, anneal it first. Just out of curiosity, why can't you anneal a nickel plated case, that is if it is indeed nickel? The brass underneath the nickel will still get hot and soften, as it's supposed to.
You would have to trim that brass, more than likely, as I think the necks are longer to begin with.