Do not claim to be God's gift to reloaders, but Bullseye is among the fastest burning pistol powders made. It is NOT listed as a shotgun powder by Alliant in their tables. Cannot help but feel you are courting disaster using that to drive an ounce of shot- shotguns operate at an order of magnitude difference of pressure. Red Dot, Green Dot, Clays, etc were made for shotshells. Bullseye was not.
What we have here is... failure- to communicate.