I was helping a friend yesterday, bore scoping his rifles to see if his cleaning techniques were Ok.
20 Vartarg
221 FB
222
22 Beggs
22/250
all custom barrels. His 221 fb had loads of carbon in it, he suspects that R#7 maybe the culprit?
The 222 had a pretty serious carbon ring in the neck.
If I still had factory barrels on my Savages, I would push 4 wet patched through the barrel to remove loose carbon, then start brushing with good bronze bristle brushes from Sinclair, Pro Shot, or Dewey with JB, give each one 25 strokes, then wet patch the JB out of the Barrel, then use a copper solvent.
I don't think that it is necessary to get bore down to bare metal every time, but that carbon accumulation does get super cooked on, making it all but impossible to get out without serious Al Oxide or Silicone carbide abrasives available from Sinclair's.