No "real" reason. Just thought it would be cool to have. Never heard of anyone building a 6.8 BR. Not for compitition, just a little "different" shooter. And I'am thinking it will be used in a bolt action pistol.
Neck up "new" 6BR Lapua brass so it would be pretty soft to work with. That would give you a dummy round to cut a reamer to. Ream out the pilot hole (neck) of a 6BR body die to fit the .277 as well as a bushing die, change the bushings to the size you need and you'de be set.
And I've never seen "factory" 7BR brass so I'am thinking start with 6 BR Lapua.
I'am working with 90, 100 and 110 grain bullets and so far I've got about 5 to choose from.
It's still in the "thinking" stage but it sounds like a fun project. Got a better idea on which way to go? I'am wide open to suggestions.