Hey Dandan do you ever use flats with those directdrive types? I sold that roy richardson one with out trying one as i had heard that you can only use rounds. I do have a cheap china one that runs the same way and loaded a 15 flat mag in it yesterday and did notice that it will go up and down fine with out hanging up but you do get a side to side stroke like dale said. Does thes work to an advantage with shading or do you just stick with rounds? I don't realy like round shaders much except for some soft no-stroke direction rendering.