Having no access to the .318 WR "square shoulder" version case, nor dimensions of it either, I was only taking a guess that it could be reamed out to more common version of same caliber, BUT PERHAPS I WAS IN ERROR. If too much metal was removed with the "square shoulder" version, certainly it could not be simply reamed out to common version, because it has already been reamed beyond reverse alteration, without some serious metalwork possibly being done to rifle to return it to its original common version of cartridge. Such a thing can only be assessed after a dimensional study of the two cartridge versions, to see, but it looks as if you have already answered that question, since you have the two cartridge versions at hand. I, too, wondered if, as collector's value, as is, it would be better to simply preserve, but I cannot answer that, for I know nobody who collects such. I am certain that the "square shoulder" version double rifle is a very rare commodity, indeed, and collectors of it would be even rarer, so I seriously doubt its collector's value---short suppy, but little or no demand! Fire forming of brass can be done, easily, safely, using new brass, WITHOUT FIRING WITH BULLETS! That is, you would not be firing bullets in loaded cartridges. SIMPLY FIRE FORM WITH PROPER LOAD OF PARTICULAR POWDER AND WITH FILLING ONLY; NOT BULLET. IT WORKS WELL, AND SAFELY, AT LOW PRESSURE, SO NO WORRY ABOUT CASE PROBLEMS DUE TO FIRE FORMING. Once fire formed, simply load the cases normally, with bullets, and fire normally. I have done this a lot, with other calibers, with no problems.