The (rifle) powder metering chamber on my Redding #3 goes from zero to 100gr, whereas the pistol powder metering chamber goes to 10gr. Which agrees with your assessment of the relative load weights.
When I get around to reloading for 9mm, I'll be getting a pistol metering chamber.
See this page for details: ht tp://www.redding-reloading.com/pages/model3measure.html