I highly doubt you could make it bigger by hand turning. But I know BH209 gave me the idea about marking the drill bit. I wouldn't hurt. Also lets you know if you cleaned it all out too. So for solvent soaking. All you do is get a patch wet run it down the barrel and then wait 10 - 30 mins. I use the TC17 foam. I spray it in there and let it work. Then work on the breech plug get it all cleared out and then let it soak in the TC17 solvent. Then go back to the barrel and receiver. Finish cleaning them up and then back to the breech plug. Works for me and everything comes out cleaner then ever. Patches come out pure white. Actually my Triumph is the cleanest rifle. My centerfires are clean I just always seem to get alittle gray on the final dry patch.