Quoted:
A couple comment.
The powder charge variable should be eliminated as part of a ladder test.. you should see a range of powder charges that all shoot pretty consistently.
The question isn't whether powder will have an effect, but rather, how strong of an effect it has, especially when
interacting with other variables.
brass annealing will have an effect on neck tension and brass life.
Indeed, that's well established, and rooted in pretty well-understood science
neck vs full length resizing... this effects how much the brass is worked.
Again, that's true, but that's not the question being asked. The question is whether one gives more precise results than another, and what that behavior looks like. This is not a place to hem and haw over your experience. This is a place to conduct precise experiments, and let the data do the talking.
To be clear, I do not want anecdotal answers to questions in this thread.
The purpose of this is to explore what the data actually says, which very well may fly in the face of common thought. We will test some of these hypotheses using standard experimental procedure, which will allow us to draw some limited, but well-supported conclusions. Hopefully, along the way, we will demonstrate how people can do this for themselves in the future. Whether we allow our thinking to be changed by what we see is up to us individually, as one would expect.