Bob, What level of ease (or difficulty) did you encounter when loading the first Gr. Pl. bullet? I.e., did it practically slide down the bbl. of its own weight or not as that can affect accuracy.* Btw, fleener's suggestion about an over powder wad is an excellent one, as it really is worth using. Lastly, sometimes the kind of bullet lube used can produce poor accuracy as well.
*If too small, it can be fixed by "beagling" the mold (Google beagling). If too large, you'll need a custom made sizing die, which isn't nearly as expensive as it sounds. For example, Ammohead on the Cast Boolits site does that sort of thing.