The problem of the 270, is the general twist used by most manufacturers to stabilise a 130 to 150 grains bullet which is too slow for the longer/ heavier vlds.
If you were using a 308 lapua case with small primer pocket, necked down to 27 with a 30 or 35 degrees shoulder in a fast twist barrel then you could start to get something descent . But then somebody would neck up the 6.5/284 to 27 and beat you to it. ( it would have exactly the same performance as a 270 win.!).
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