I've been searching, but haven't found the best easiest method for making 257 Roberts brass. Actual 257 brass can be hard to find. Is it better to use 6mm brass and neck up, or get 7x57 and neck down? Less fuss is preferred.

If all goes well, I'll be trading for a 77 Ultralight. Just need some brass. I guess the other option is factory Roberts ammo.

Thanks,

Jason