Their rifling, twist rate, heat absorption, cool rate. etc. doesn't change. Their tolerances should not be different. Presumably the QC of high end ammo doesn't change. Finding the ‘right’ ammo for a specific rifle is such an accepted practice, I would've thought some investigation on this would have been done. It reminds me of when people thought it mattered whether they used ‘Shell’ or ‘Gulf’ in their cars.