Cowtownup,

The very best there is, and there seem to be VERY FEW who are this tight, is 5-7% total BR variation. MOST have a nominal variance of 5-8%, so that 8% could be up or down, allowing for a total swing of 16%.
I have lived through much more than a 10% swing from Varget.

A word of caution for you, about to much faith in QL. Anything coming out of Eurenco, they are all too happy to tell Hartmut anything he wants. Beyond them, no one tells him Shyte, and the Pressure Trace confirms he REALLY struggles to accurately describe General Dynamics powders; especially the ball powders. So the only way for QL to know about them is Bomb Testing. Unfortunately this is not only very expensive, but limited in description of a powders abilities. Really isn't much more useful than a burn rate chart. So while it is very intriguing, and fun to play with, don't think that it will actually tell you the pressures you are running, or how the burn curve looks.