I thought as long as you use the larger disk under a smaller disk then you were fine. At first thought you would think it wouldn't work, but the rotating motion fills the wider open cavity. I know the Adjustable Charge Bar works well in this same manner. You would think the large opening of the Adjustable Charge Bar under the small round opening wouldn't work well, but again the rotating motion ensures proper filling of the cavity. The ball powders work the absolute best with making all this work. But if you use a smaller cavity disk over the larger then as the powder drops you would risk powder resting on the shelf of the smaller disk not drop. But I bet small over large will work fine. I hope I'm not talking out my behind. But I really bet it will act the same as my Charge Bar.