As other guys have said, I agree completely with borrowing a chronograph and also trying some first run bullets. Blems are blems for a reason. A chronograph will really tell you what's going on with the overall consistency of a load and you can also compare that with your actual group size on paper. Personally, I would not be concerned about differentiating between tenths of a grain in powder charge difference until you have first shot groups in .5 grain increases. Furthermore, even though each rifle is it's own unique animal in what it prefers, I have found that middle of the road powder charges generally provide the best accuracy for me. 41.5 grains of IMR 4895 has been known to generally produce excellent results, although out of your specific rifle it might be different.