From what I've read over on snipershide brian tooley had made this wild cat cartridge from necking up rws 8x68s cases to 375 then back down to 30 then fireformed for a good 10 plus years prior. When brass got short one of the ruger guys said hey lets use a 375 ruger case instead. Then the throat was appropriately decided upon for long, heavy for bore, pills. At least thats my understanding of it. Could be wrong though.