Dave,
#3 was with my home casted 420 grain and 70 grains of Triple Se7en 3f and a wad. They shot lower then the heavy ones before which again surprised me.
Simisane had it half right. In addition to there being heavier recoil, the main factor for heavier bullets hitting higher is the increased barrel dwell time. For any given powder charge, the bullet that is heavier moves more slowly down the barrel, giving the barrel lifting recoil force more time to lift the barrel. So in essence, your barrel is pointed higher with the heavier bullets than with the lighter ones. This trivia is more important to understand when you are using a fixed sight hand gun.
James