I have resized 8 mm Remington mag brass on several occasions, with good success. You must however, make sure your resizing die is bottomed out, and you must use lots of lube inside the neck. It will get you through in a pinch. Once in a while, you will split a neck. I have done this in the past, it works. The 8mm mag is the original parent case, as it is Layne Simpsons brainchild. Maybe someone will make some affordable brass that is decent. I have about 200 pieces of unfired brass now. Some of it is premium factory ammo. I bought it cheap from a guy who did not load, and sold his gun. I would have bought that to if I knew he was selling it. The last batch that I resized, shot well, and I got several firings from it. I neck size every other firing. Hope this helps.
AIM SMALL, MISS SMALL.