I've spent most of December trying to get my Kadet barrel clean, maybe for the first time in nearly 50k rounds. I tried Kroil, JB compound, Hoppes, brushes, brushes with patches, patches soaked in combination of solutions and pastes. Still the barrel and rifling isn't completely free of what looks like lead and carbon through an inexpensive borescope.
I've tried to take photos of the screen of the borescope, but the resolution of the monitor is just not good enough to show up well on a photograph or video. Suffice it to say I can see changes in the barrel with each cleaning.
The last thing I tried were the VFG pellets on a screw type jab, again, with various combinations of solvent, JB compound, and Kroil. This looks promising, I think because the uniform pellets put enough pressure against the debris to make whatever else one is using work.
The Kadet has been shooting very well since the last cleaning but it still won't stay that way, like it used to, when it could go several thousand rounds without anything but a chamber brushing. At first, I thought the barrel was shot out, but the borescope just said it was still dirty, just not as bad as it had been, with globs of lead filing up the rifling.
I've got one more .22 to try the pellets on. It is a Savage heavy profile .22 bolt gun rifle that shot very well when new, then deteriorated to the point it was getting frustrating to shoot it so I put it up. I am going to work it over with the pellets, etc. and see what happens. I've already spent some time getting the debris ("black ring") out of the chamber area, but don't have a long enough rod to push the VFG jag the length of the barrel yet. Parts coming.
A borescope is useful, but the real test is at the range, where I can introduce enough other variables to really complicate things!
More later this week. I'm interested in other people's experiences cleaning really fouled firearms.