Darn, this post reminded me of something. I have a set of Lee dippers I seldom use. I prefer to use the 30 or so dippers I've made over the years that are all altered Lee dippers. I've charted the grains of powder each will consistently throw for around 16 different powders. I've spent many an hour with a couple of different digital scales confirming the grains of a particular powder they will throw. I'm very comfortable using them. I may be off a minor bit on grains they throw, but feel my charges in reloads are consistent with them.
This Monday, I should receive a delivery of rifle powder from Powder Valley and there are several powders I've never used in it. Powders I prefer to use are just not available and was forced to find new powders for cartridges I reload. Darn it! Have to spend a fair amount of time figuring out the grains my 30 or so dippers will throw.