I have been very successful with I.M.R. 4350 powder, Federal 215 primers, Winchester cases and the same bullets.
Load for the 270 grainers was 82.0, too much indeed for the 285. On game, the performance was excellent, sudden death for everything.
Good luck

Erik check out the beginning of AR the reloading pages
my rifle shot 300gr BTSP great and all animals never complained they just dropped..

Mike

Erik,

Is N150 about like Reloader 15 or Norma 203.

I would move to the next slower Norma powder, is it sill called Norma 204? Work around the 78 grain mark. Quite often when an accurate rifle will not shoot well with a given bullet then using a powder that is it a bit slow for the bullet/calibre combination will often allow it to shoot OK.

Mike