Hi Louis, yes I already did that using RWS ammunition and it's the same.
Currently I have tried many different propellants, loads and seating depths all made taking great care and using Norma brass.
Nothing is even looking like consistent, it's like a shotgun with a 6" radius of bullet impact @ 100yds.

I have a strong feeling this may well be a re-barrelling situation, but if that's the case, it will be rebarrelled as 6.5x54MSch