Yes that is what i was told, Chey-Tac is comisioning Sierra to design a Match King bullet for the new 375-408cheyenne tactical cartridge, suspect it will be the bullet offered in their loaded ammo. I was told that there will be some test bullets arriving soon. Lost River Balistics designed a special bullet for this caliber also, this is one of several bullets they have been testing. As we all know the LRB bullets are monolithic and $$$. They have been testing the accubonds with very good results. I was told at 1500yds the groups were 10-15" across the spectrum of bullets tested. The LRB bullet had the least amount of MOA needed.
I have no idea when the bullets will be avalible. I think they want to test a range of weights and see what works the best. 325-350grns is the range they are looking at.
Here is a pic of a formed 378 snipe-tac case and a std 408 case for comparison. The bullet is just a plain Sierra.
I may order a box of the LRB 350grn for testing later on.