Hey Darrell. I had the same problem when trying to throw 5.6 grains of Winchester Super Field. Came up .2 grains short. So, I took some emery cloth (do not recall what grit), rolled it up, inserted it into the disk hole and removed some material. Mind you, I had to reassemble / disassemble the powder system 4 or 5 times. Either I am good, or I just got lucky, as I did not exceed 5.6 grains.
I figured I would have to drill it out or open it up somehow. Just need to test the load and see where to go from here.