A while back Larry Gibson did some tests with Bullseye for the 44 Magnum and 44-40. I reposted that information to the 44-40 website with his permission as well.
I recently updated the 44-40 website by adding a Bullseye Powder history section for the 44-40. I have photo examples of the Bullseye powder cans from 1899 to about the mid 1930's but could use some help dating powder cans after the 1930's. I elected not to add any of the cans until I can get some dates. The can Larry used was of the square type, maybe from the 60's
What I have so far can be seen here: https://sites.google.com/view/44winchester/chasing-the-44-40/powder-transitions/smokeless-powders-transition-years/bullseye
I also added a Unique powder page: https://sites.google.com/view/44winchester/chasing-the-44-40/powder-transitions/smokeless-powders-transition-years/unique
44-40 Website - https://sites.google.com/view/44winchester/chasing-the-44-40