Any issues with superformance being temperature sensistive? Id hate to make a load that work well in the winter but is over pressured in the summer and vice versa?
Could try R26. Guys are getting great velocity and ES. It is however not the most temp stable. R23 is suppose to give close to the same velocity as R26 and is more temp stable. I shoot a 6.5X47 with H4350. Would also be a good powder to try and is temp stable.