Some powders are less positionally sensitive than others. Some cases are less positionally influential than others. Some bullets are less sensitive to base pressure and jump than others.

What are you wanting to do with this rifle? That’s the first question I ask myself, because it tells me how hard I need to scrutinize my results. How I grade a 0-300yrd load to kill deer with a 45-70 is very different than how I grade a 0-800 coyote killing load, and still different how I grade a 1400yrd precision rifle match load, and still different than a 100/200 benchrest load, still different than a 600/1000yrd benchrest or F-class load.

I think powder selection is often over-thought. In my experience, guys do WAY more load development on average than they should. Hunters don’t really need sub-moa loads, but any of half a dozen powders under half a dozen bullets will usually get them there without much handwringing.

Alternatively: Benchresters and F-classes either have used a similar cartridge themselves, or know other benchresters, so that world seemed to be almost 100% experience based, with most of them never cracking a manual. Most of the Precision Rifle competitors I talk with at matches or on our state club pick up a load using one of 3-4 powders used for ALL of the cartridges in our game. Guys will hand around experience, giving others major short-cuts, rather than recreating the wheel. As an example, I wasted about 50 shots in my 6 creed last winter. Two competitors handed me “105 Hybrid 5-10thou off, 40.0 or 42.0 H4350.” Foolishly, I worked up from 39.0 to 42.7, but BOTH nodes were exactly where they said they would be.

I went through a phase reloading where I would burn POUNDS of powder looking for a load, but I have come around to realize for anything but benchrest shooting, I can find a 1/2-3/4moa load without trying more than one or two powders. I might ask another competitor or reloader, ask online or google “best powder for _____,” but I almost always look at the case capacity compared to something else I have loaded before and build from there. If I ever catch myself again loading 5 powders and taking them to the bench for a single cartridge, I know it’ll be my time to hang it up.