Since we're getting into cleaning, with abrasives, I'm compelled to bring in a point about it.
WE DON'T EVER WANT TO 'POLISH' A BORE.
Polishing is a dangerous misnomer for lapping. If you do polish a bore, copper fouling will instantly go through the roof.
And truly, the only way to fix a polished bore -is re-lapping. But if you got overzealous with your polishing, enough lapping to fix it, will also break it. The bore was just plain ruined.. I did this, I have a friend who did it, I read where others have..
- Don't ever use Flitz in a bore
- Don't ever use J-B 'BORE BRIGHT'
- Use J-B 'NON-EMBEDDING BORE CLEANING COMPOUND':
J-B® NON-EMBEDDING BORE CLEANING COMPOUND | Brownells
This, in frequent but rational use, will not harm the best in lapping, as it actually matches it.
When you feel a constrictive rough spot in a bore, break out the J-B and work on the spot for a minute. Done,, didn't hurt a thing.
If shooting moly, plan to J-B the first few inches, and soon you'll feel another spot ~10" down the bore. Then work both areas every time you clean. The ~10" area is where vaporized moly re-condenses, and re-bonds to itself. It takes a while, but this is the area that will kill accuracy, because once it's undeniable, it's too late...
Sounds like a lot of work, huh? YEP