On his website David Tubb says: “A detailed study of large and small rifle primers showed that large rifle primers worked best when the propellant charge exceeds 35 grains as is the case with the 6XC.” I would consider Tubb the last word on the 6XC.
Since the 6.5 Creedmoor normally uses more than 35 grains of powder, I haven't bothered with the small-primer Lapua cases, partly because I've had such great results with Hornady brass.
