Re: 7mm WSM or .284 Win???
Lapua and Norma make 284 type brass.
300 and 270 WSM brass is available form Norma, as is 300 SAUM brass. I have a 7x300 WSM which, for all intents and purposes, is a 7 WSM... except that I can order Norma brass for it. The Norma is every bit as good as Lapua in my experience.
You can make 7 WSM brass from 300 WSM brass but it requires necking to a false shoulder and fireforming, much like an AI version. To make 7x300 brass you just run it through the sizing die once, load, and shoot.