So Rock Fish, if I were to drill a 1/8" flame channel from the primer end, I wonder how long I should leave the flash hole to maximize ignition yet minimize blowback? Right now I'm still inclined to go with Chap's suggestion and leave the plub along until I can try a hotter primer. If that doesn't work, I can start drilling the 1/8" flame channel a little at a time and see what works.