I just got a Lyman flash hole uniforming tool and am not positive on how to use it. Does the tip-end of the cutter ream out the I.D. of the flash hole to 0.090" (dia. of cutter tip-end) and then the angled part behind the .09" cutter shaft, does that chamfer the end of the fash hole. The reason I ask is because the flash hole now is about 0.075 to 0.080" and the tools tip is 0.090", so I either just use the tip to chamfer the inside end of the flash hole and leave the I.D. as is or I ream it out to the 0.090" I.D. I thought this was a deburing operation at the inside edge of the flash hole only and not an operation to enlarge the flash hole to one size and chamfer the inside edge also. So should I go through the flash hole with the tool tip and open it up and then alittle deeper to chamfer the inside edge?

Give your best shooting efforts to 20 unaltered cases and to 20 that you've uniformed. Use the very same powder, bullet, seating depth, primer-- the whole nine yards. If you see a demonstrable and positive difference in your group size over the unaldulterated ones, then do to all your cases what you did to that original 20. Sounds like a good excuse to avoid mowing the lawn or washing the dog this weekend.

As a last resort, consult the Lyman website (http://www.lymanproducts.com) or send them an email. Most outfits have a "Contact Us" avenue somewhere on their websites. There's a PDF with directions for use of this tool there.

As is often the case, Steve Wagner has an informative riff on his site covering just this topic.

Don't specifically know the Lyman tool, but I'd just use it to chamfer, I suspect.

Good luck,

flaco