The 6.5-284 obviously has some intrinsic accuracy advantage over the 270 Winchester judging simply by the number of competitive LR shooters using it and the number of records it held/holds. Never seen a 270 Winchester at a single match, not one. I also perused PS magazine match reports for several years and not a single one showed up. That doesn't mean it isn't accurate just not to the degree that some of the other chamberings are.
There is no reason why someone couldn't make a 9 twist barrel and shoot 160 grain VLD 270s in it if it was so good. Unless the factories switch to a 9 twist we will never see a good selection of 270 bullets for long range work. Who would buy them if they won't shoot in a factory rifle and nobody in their right mind is going to try and compete with one unless trying to prove something.
I will say this, I know gunsmith here in AZ that has chambered a number of 270AI and although it gains little in velocity, they have proven to be quite accurate. Might be something to that!
