Bob is right, if you don't use a bores-cope, you don't know
I can echo Bob's story exactly. I always cleaned with both TM solution and Sweets until the patches came out white. Sweets gets the copper out, but little did I know I was merely polishing the glazed on carbon and not getting it out until I got my borescope. When I discovered the glazed carbon, I tried everything to get it out without brushing. My local gunshop said if I soaked wipe-out in the barrel overnight, it would get anything out. I soaked it for three nights running and it didn't even touch it. In the regular steel factory barrels, the center of the barrel would be the only area clean of the carbon. Just ahead of the chamber, ignition causes great heat. At the end of the barrel where the bullet is travelling the fastest, bullet friction causes great heat. The center of the barrel stays coolest. In my stainless Remington factory barrel on the .223, the carbon was only at the chamber end. These barrels had all been religiously and fanatically cleaned from the get-go. Lapped custom barrels are apparently easier to clean. I used the same methods on my Bartlein .243 barrel and it had only a fraction of the glazed carbon in it that the factory barrels did
Anyway, it took the strong compounds with a brass bristle brush to finally get everything clean. Flitz works, but I would recommend Iosso or JB instead. Flitz will get the bore a bit too smooth. Nylon brushes just didn't get it, even with Flitz (I tried that on an old .308 factory bore that I wasn't too concerned about).
It's possible that some folks are getting their bores clean without checking with a borescope, but I'm willing to bet that MANY who think they are, are not.
After getting the barrels clean, I started working on what works to keep them that way. After my next shooting session with the stainless .223 I used the old routine with the TM solution and Sweets, brushing both with a nylon brush. Like before, Sweets got the copper out but TM did not get all the carbon out. I decided to try the wipe-out without letting it set overnight. It didn't get it out with the nylon brush, but it did with the bronze brush. I have more testing to do. I would like to find something that will work with the nylon brush for regular cleanings.
Then there is always the big question, just how clean does it need to be? The guns always shot well after my standard cleanings. Perhaps it simply is not necessary to get them down to bare metal each time.
