i noticed it with pyrodex but also with T7
I havnt played enough with the real black powder to know how it does but Phil told me something that i never thought of.
Always shake the powder, just moving and pouring it can seperate the powder. Like say even though 2F is larger little bits still get in there and break up like 3F those can worm their way down and the big stuff can float up. Keep it mixed so those little pieces stay mixed with everything else.
Its hard to get things out of some of these older guys that have been doing it for years. Its like nascar no one wants to give out to many speed secrets and get beat but every once in a while they let little good bits slip out.