From powders available in Scandinavia I would suggest Norma MRP or Vihtavuori N560. Norma MRP_2, new magnum powder is bit to slow to get top velocities for 6.5 (above 2600 f/s). Maybe compressed, but I never tried.
Slow powders is a must for 6.5x55. This an overbore cartridge.
I don't know where you are located but if in US then getting Norma or Vihtavuori may be difficult. I would suggest following US-made powders (some starting charges/expected velocities aprox):
Ramshot Magnum (Big Boy) 47.0 grains / 2500 f/s
PB Clermont PCL 517 47.0 grains/ 2500 f/s
IMR 7828 44.0 grains/ 2500 f/s
Alliant Reloder-22 44,0 grains/ 2500 f/s
Winchester WXR 44,0 grains/ 2500 f/s
Anyway, you'll get best results with Norma MRP. In perfectly safe load you should be able to do slightly over 2600 f/s. That's what I got from 22" barrel
Hope it helps
Roman