NBRSA/IBS Hunter Rifle competitors have been using wild-cat versions of this case type/capacity since almost day one; they were very popular until the mid-1980's. The GOOD news now, is that there will be precious little case forming required: simply neck -up for the .30x47s and neck-down for the 6mm; 25s etc. Of course, about the time the various 6mmX44-47mm variants disappeared from the equipment lists,around 1988), we were still trying to shoot 68 Gr. bullets, as opposed to, for the roughly 45-49 Gr. capacity cases, the better balanced 85-100 Gr. range of bullet weights.
Two attributes killed off the various 6x47 type cases: 1) difficult case forming,moving shoulder back to the point that the original shoulder material wound up in the middle of the newly formed case neck) and the lack of [GOOD] FL re-size dies; 2) the difficulty of maintaining a COMPETITIVE TUNE with the relatively large capacity,for a 6mm and 68 Gr. bullets) combined with a much narrower powder selection. While delivering the required 45.5 Gr. H2O capacity, the 6/250 had the well deserved reputation of getting "sticky" just about when the sweet spot was found - case life was brief. Sadly, in THAT era, FL sizing was regarded as TABOO!

Knowing now,that FL resizing is a GOOD thing), what we had abandoned then,in BR circles, FL resizing of cases was thought to degrade precision), the 6/250, teamed with a properly dimensioned chamber and FL re-size die, should work extremely well! For a short time, the 6HLS,essentially, the 6MM Rem. reamer head-spaced on a .22/250 GO gauge) enjoyed more success than did the 6/250 . . . but it too withered on the "difficult" case vine.
Back to the point, once we have brass which requires NO movement of the shoulder, it becomes much easier for most people to make GOOD brass. So, most variants of the new LAPUA 47MM brass should prove excellent for many applications - it will certainly be better than using the now popular .308 LAPUA and/or other longer parent brass to form these types of cases!

R.G.