I never run a drill bit through the flash hole. There is usually a small burr inside the case that I never worried about for years. Then all the talk of needing to remove it got me to try it. I made a de-burr tool with a drill bit and a 1" dowel, works great, didn't do a think to improve accuracy that I could measure. Of course I don't measure my group's to a thousandth of an inch either. I think time is better spent practicing with a one or even one and a half inch rifle than trying to get a quarter inch rifle to shoot a thousandth smaller group with a hunting rifle!
