If I were to design one from scratch it would a something like a shortened 300 Norma improved necked down to 7mm something that would fit on tikka action/medium length and still have a 40 degree shoulder. No idea how I'd do it or why but I was thinking about this very thing the other night. Wondering how the wildcatters before looked at a Case and said if cut this down and take out the taper and move the shoulder forward it will do X. Always thought that was really cool.