Go easy and you’ll clean the channel without opening it up
You will never "open up" the flash channel with routine cleaning with a 5/32 drill bit (by hand) and even if you managed to do it you wont hurt a thing. The flash HOLE though is an entirely different matter. Just removing .005 of material from the flash HOLE and the plug, nipple or vent liner is likely toast. Thats why you buy a Lehigh bare primer plug made from 17-4 stainless with a removable vent liner. About $6 then to place when needed.
