As reported by TFB:

Developed by SIG SAUER, the 277 SIG FURY was introduced with a maximum average pressure of 80,000 psi, with a 135-grain bullet traveling at a velocity of 3,000 fps.

Developed by Weatherby, the 6.5 Weatherby Rebated Precision Magnum was introduced with a maximum average pressure of 65,000 psi, with a 140-grain bullet traveling at a velocity of 3,075 fps.

Developed by Olin Winchester, the 6.8 Western was introduced with a maximum average pressure of 65,000 psi, with a 175-grain bullet traveling at a velocity of 2,840 fps.

There is a small error in the second page of the .277 Fury, a twist of 7" is not equal to 254 mm.

But the selection of a 1-in-7" for a .277" bore is interesting, it's even shorter than a 1-in-8" in .308".

EDIT : and the 175 gr listed for the 6.8 mm Western is strange (170 gr is already pretty heavy for .277").

Ultra long range cartridge I'm guessing; so you're going to want a long streamlined bullet to make it easier to hit.

Farmplinker said:

Ultra long range cartridge I'm guessing; so you're going to want a long streamlined bullet to make it easier to hit.

Seems improbably heavy. Same SD as the 250 grain .338 if it does actually exist. 

Yes, there is a significant length available outside the case, but the heaviest .277" bullet I know of is the Berger 170 gr EOL with a C7 of 0.339, already better than the 250 gr class of .338" bullets.

Hence my comment, maybe someone knows about this 175 gr / .277"?

EDIT : another offspring of the .404 Jeffery case, and a "long range" version of the .270 WSM?

I'm sure The Firearm Blog, or at least the websites of some of the gun magazines will give us the information as soon as they can.