With the limited load testing that I have done, I have found that I can still get acceptable accuracy by going 0.3 grains above or below my node.
For example: just worked up a load and found that my node was at 40.1 grains of H4895, outstanding accuracy. To test my load I loaded a total of 3 rounds each of 39.8, 40.1, and 40.4; shooting one round of each into three seperate 3-shot groups.
Each group contained one round of 39.8, 40.1, and 40.4 with the result of three groups all measuring right around .5" at a 100 yard target.
So I guess I would say that my nodes are typically around 1/2 grain wide.
EH