One thing you should find somewhere in all these different sources.
CONSISTENCY in your method, even movements impact precision.
On a Dillon 650, I run almost 20 rounds before I start seating just to get the powder measure performing because if the powder sits vs is moving it makes a difference how much it throws.
I also made sure I use a dryer sheet on the powder measure to kill the static elec.
but the most important thing by far is if the loader is aware of things like how you work the handle needs to be consistent... is ultimately how things come out different or not.
