Here is what I did when working up loads for my 45-70.

Since there was such a huge range to load powders like IMR4198, I started at 43gr, then loaded some 45's, then some 47's, 49's, and 51's. I like to load up 6 of each. I will usually load up my starting load at 9.

Here's the reason. I like to have at least 2-3 fouling shots and to get sighted in enough.

If I get a good group, I would like to repeat it. If I get two good groups with a load, I know it has promise, and never time I load around that load and finallize it second trip out.