Following I add some more pics from www.armiestrumenti.com, in this case it are not taken by optic instruments but by electronic microscope (SEM). You can note that 3N38 powder has not simply cilindric grains but forated cilindric grains (about 30..50 um hole) to increase combustion progressivity:

- VV N340 -










- VV 3N38 -






- Hodgdon BLC2 -