I'll chime in a bit.
Ruger No.1. 30" Pac Nor 1in8" twist in .277. 270 win case. 56gr of H4831. Berger 170gr EOL. 2940fps.
This rifle will stay around .5 MOA depending on my day at the range. It's not a benchrest type of accuracy but getting there real fast.
Now a .339 BC out of a .277 is quite amazing if you think about it. For the most part none of the 6.5's are in that class that I know of but limited on knowledge

. It takes at least 180gr bullet in a 7mm to get there and 210+gr in a .308 to match or over come the BC.
I'm not saying it's the best, I'm not saying it's going to take home any awards. All I'm saying is it's about damn time the .277 has got a boat that will make the voyage with the rest of them.
Just for the kicks of it, if you were to put the new .277 bullets in a ultra mag or nosler case with all that capacity. I do believe there would be a light weight contender in the ring. Do they need to build the 27 Nosler as a commercial round? Yes I do believe this is a must. The reason this is not come to light is the 1 in 10" twist of standard .277 rifles made across the country. Things are about to change for the .277 fan club. Give it a few years to catch on. Hornady should of looked harder in their new line of bullets.
I'm bias on this subject because the 6.8mm has been way over looked in all aspects of the perfect medium range class of bullets for long range shooting and hunting.
BTW my load catches my 300WM using 165gr bullets going 3260fps on muzzle energy at 750 yards. Going 300fps slower at the start. So says the calculators. So it is a viable long range hunting set up. Now imagine stamping a magnum on the case and see what she'll do.
I know I'm just spouting and about to get slack, but I'm a 270 fan and it's about to get a following in the long range crowd. But that's just my theory, there's a lot of hard headed folks out there. Over bore pffft. Lets just say most of the super mags are over bore and be realistic. Because you just shortened all the barrel life on all them.