I've thinking in a solution for those carbon rings you mention in your posts.
Really I don't have such problem, but it may happen that it is related to high loads and a certain burning rate of the powder.
Anyway, I wonder if you have ever thought in using a steam cleaner for such purpose.
I don't know if it is a widely used device for the housewife in your country, but it can do the removal of the carbon rings very easy and quick.
In Europe it is a common device, and can be found almost everywhere, at a very cheap price while you stick to the basic models.
A different thing is when you move to the large, high production ones, which are much more expensive.
For removing / cleaning the bore you just need a metallic hose properly bent to carry the steam from the steam cleaner into the chamber, and to place the muzzle downwards into a bucket.
Just a few strokes with clean patches afterwards, to dry the bore and that is all.
My two cents.
Really I don't have such problem, but it may happen that it is related to high loads and a certain burning rate of the powder.
Anyway, I wonder if you have ever thought in using a steam cleaner for such purpose.
I don't know if it is a widely used device for the housewife in your country, but it can do the removal of the carbon rings very easy and quick.

In Europe it is a common device, and can be found almost everywhere, at a very cheap price while you stick to the basic models.
A different thing is when you move to the large, high production ones, which are much more expensive.
For removing / cleaning the bore you just need a metallic hose properly bent to carry the steam from the steam cleaner into the chamber, and to place the muzzle downwards into a bucket.
Just a few strokes with clean patches afterwards, to dry the bore and that is all.
My two cents.