Homebrew PCBs

I'm looking for a method to deburr my ground vias to smooth the drill hole for copper plating. I do RF prototypes and the PCB has a lot of ground vias. In the past, I used 2 pass drill to drill the hole, the 2nd pass, one 1 mill smaller but it doesn't seem to help much. I can increase the diameter of the via hole up to 50 mils.

Thanks
Lanny