Johnathan and Toby, i told a bud about 257 WBY brass over at Buffaloarms.com, he bought a couple hundred sticks of new Norma [WBY] for around $1.80 each iirc, i have one of Roy's early 12 twist FN Southgate rifles in 257, i size only 0.257" of the case necks and never push the shoulders back, the brass lasts several firings, that said, i dont lean on my rifle too hard, being 12 twist, it will only stabilize the 100gr TSX and little 100gr A-Frames at a very easy and accurate 3500 fps with 65gr Norma 204 powder, that modest charge of powder is easier on the throat and the ears ; ] it simply melts white tail deer and pigs, it's a great round and Roy's crew done really nice work building the old FN rifles.
Good luck on the brass, hope Buffaloarms has some in stock for you men.