It's a long story and perhaps slightly off subject, but a beater low wall I got years ago is approaching shootability as a 256 win mag. Cases are very pricey and a bother to make. I happen to have several boxes of new unprimed remington jet cases. I'm looking for opinions (not likely to find actual experience) on the feasability of fire forming the jets into 256s. Both cases are the same length, same diameter in front of the rim, and the same dimensions for the first half inch in front of the rim.   

If I try this does anyone have a suggestion for a fire forming load? With a bullet or wad of wax? Would it necessary / wise to anneal the jet cases before fire forming despite their being unfired - they are old? My thought is to fire form them in the low wall rifle.