The only flash holes I'll deburr is for my .308 and .300 Win. Mag. long range target rifles. I honestly don't know if it helps or not. I figure that if I'm being totally anal with all of my case prep, I might as well go all the way and do it, thereby leaving nothing to chance. With Lapua brass the flash hole is drilled not punched, so the burr is little to non existent. I can't see the purpose of doing it for pistol ammunition. Bill T.