I have a 351 PD and don't get any unburnt powder flakes anywhere.

Usually just go out and shoot a box of 50 Then stick it back in my pocket.
I only shoot Speer Gold Dots {bought a brick} no sticking of cases what so ever. The first cylinder full to the last cylinder full.{I was concerned about this before I bought it because of the Aluminum cylinder}

Love this little pea shooter.