I know that Pac-Nor makes a 5 groove 1-8" twist 270, but I know of no other company that cuts a 270 barrel any faster than 1-10.
If they did I am sure there would be more demand for long slim heavy 270 bullets. But most folks think of the 270 bore as a hunting rifle and not a target rifle. I would bet that the 270 would beat out the 7mms and nearly keep up with the 6.5s if such bullets were offered, but if pigs had wings they might fly.
In all honesty having a whole new market section opened up for .277 long range shooting would be redundant. I know the math shows that it will beat the 284s and the .308s, but it's largely just number crunching. The truth is that the game is over complex now, and most shooter concentrate too much on gear and not enough on skill.
I love my 270s. In fact they are one of my all-time favorite calibers, but I have lost nearly all interest I ever had in target shooting.
For long range I have found nothing in my 52 years of hunting that has convinced me that any other shell really beats the 270 by enough to make me want to buy one. I have made a long shot once on a moose with a 375 H&H, but other than that one moose, I cannot recall any game animal I have ever killed over 500 yards with any rifle caliber other than a 270 Winchester, and I have seen maybe 30 head of deer antelope and elk killed by men I was hunting with with larger more powerful rifles, but none of them really killed the game any faster than my 270s.
Several were as good, but I can't say I have seen anything better so far.
When I was shooting long range with my hunting rifles I didn't go "all-nutso" over slick
"new-improved" anything. I used at 500 to 900 yards what I used at 100 to 200 yards. Mostly Nosler Partition bullets and a few others thrown in now and then. I learned over the life of 3 rifle barrels what to hold over, at what ranges, and that what I did.
Anyway, I do not know if there really is any call or need to shoot anything heavier than the 160 grain Nosler. Maybe, but I doubt I'll live long enough to see enough testing of the idea to impress me.
In my 52 years of hunting I have used many different rifles and caliber as well as a lot of different bullets. As a gunsmith I have made many hundreds of rifles in so many calibers I can't count them and I have shot all of them to some extent.
I own a 300 mag, and I have owned several 6.5MMs 7MMs 300s and 338s in the past. All were used to kill game. All worked very well. But the truth is that none haves really seemed to kill any faster or any better than my 270s. Many were not really quite as good.
I would assume that a hit with a 250 grain 338 on an elk at 1200 would have a faster killing effect than a 150 or 160 grain 270 on the same elk at that range, but I don't do that. I see no reason to try and I see several reasons not to.
Real world experience has shown me that at ranges out to about 700 the extra power of the faster bigger magnums is not really doing a better job of killing game. it doesn't hurt, but I can't say it helps.
These days I have pulled back from the "long range game" when I hunt. It's not fun for me anymore. I keep all my shots at 500 meters or closer, and I prefer to be MUCH closer.
Just as a note of interest, here is a 160 grain Nosler Partition I took from the neck of last years elk. 270 WSM, about 400 yards away. Hit in front of the left hip about 10" with the elk angling away from me strongly. Bullet went through the whole length of the body from entry to the right side mid neck, and was found against the skin. This was the 2nd shot. First one hit broadside and exited the other side, but I under estimated the wind and hit the liver instead of the lungs. The elk turned to go away from me so I shot again. When I gutted it out I found this 2nd shot was probably not necessary, but I keep shooting if they don't fall. Most do fall, but this one didn't, so I shot 2 times.
The bullet still weights 129 grains.