I have fought this before. Very similar experience with accuracy once a persistent crud ring has formed. Not sure what rifle/barrel you are shooting but the more stubborn cases of this I have had have been in percussion t/c rifles. First step is always thorough cleaning then start evaluating/changing variables to try to eliminate the ring formation.With that, this thing really wants the bore swabbed between shots. 1, it gets very hard to seat the patch and ball past that “ring” if you don’t swab the shots go haywire consistently.
Was the ring there to some degree when you started shooting and then got progressively worse or did it appear suddenly?
Based on previous posts, looks like you are shooting 70gr 3f swiss, .015 prelubed traditions patches and .490 swagged hornady balls correct?
Any history on cleaning methods/schedule used on this rifle?







