Dennis,
Claiming that since .270's aren't used for target shooting 6.5's obviously have some intrinsic accuracy advantage is faulty logic.
The reason 6.5's are used for target shooting and .270's aren't goes back, again, to the history of the calibers. If the .270 had appeared first, in a shorter military cartridge with a sharper shoulder and faster-twist rifling, it probably would have been a top target caliber.
First, most early smokeless target shooting was done with military cartridges. Second, the .270 didn't appear for 31 years after the 6.5x55, the first commonly used 6.5 target/long-range cartridge. Third, the .270 had a relatively slow twist, so nobody developed longer, higher-BC bullets, which happened very early on in 6.5.
Fourth, all indications of any "inherent" accuracy revolve around the case itself, not the caliber. They normally involve a short, relatively fat case, with a shoulder angle of around 30 degrees, give or take a few degrees. This fits the 6.5x55 case far closer than the .270 Winchester case--and no other .270 cartridge appeared until 50 years after the 6.5x55.
When 140-grain 6.5mm spitzers were being widely used as both match and long-range military bullets in 6.5x55, the factory 150-grain .270 load used a ROUND-NOSED bullet, because that's what everybody believed was needed for "woods" hunting.
And the primary 130-grain .270 load was designed for flat shooting to 400 yards and not much farther, because that's all hunters could take advantage of back then, since very few rifles even had scopes. They didn't care how much a 130-grain bullet would drift in the wind at 1000 yards. Instead they wanted a bullet that shot flat enough so they could hold on hair at 300 yards. And a 130-grain .270 bullet at 3100 shoots much flatter out to 300-400 than a 140-grain 6.5x55 bullet at 2700.
The two cartridges were developed for totally different purposes, which influenced their bullet designs. Nobody but a hobbyist would go to the trouble of developing, say, the 6.8x55 or 6.8mm Creedmoor just to prove (or even test) if .277 bullets were more intrinsically accurate. Why would they be? But there's also no reason they'd be less accurate than 6.5mm or 7mm bullets.
