Hey Sarg - that powder looks like a mix of mouse nest and attic bat droppings. Can be found in most old Ontario houses. Very enlightening to see the cross-section - thanks. Note there is no wad between the bullet's base wad and the powder and there is actually a step inside the case's paper liner to stop the wad from 'falling' to the powder. The inner paper liner actually reduces the inner capacity to better utilize the 'nitro-for-black powder in the load.
: Really good photo's with useful information for handloaders.