I found a better than usual powder burn rate chart. Most powder burn rate charts rank powders unevenly, so that, for example, powder 12 might be 10 times slower than powder 11, and powder 13 might be 1.01 times faster than powder 12. This chart ranks them somewhat more realistically. A better job could be done by an independent laboratory, but the powder manufacturers would probably not cooperate.
I've noticed that too,I've poured a little out before and lit it too see how fast it would burn just for the heck of it and have seen powders that are suppose to be faster burn slower and vise versa.
Smokeless powder is designed to build pressure progressively. Burning it at atmospheric pressure gives no indication of it's behavior in a cartridge. Fast target powders like Bullseye are designed to burn efficiently at relatively low pressure, producing highly repeatable low velocity shots. Bullseye is designed to operate between 9000 and 14000 psi, just a wee bit above black powder. I don't know poop about rifle powder, but a slow pistol powder like H110 is designed to really start burning at around 25 ksi, and to perform optimally at pressures around 35ksi. I know a little bit about energetic chemical processes if anybody has specific questions about powder behavior.
