Get an old aluminum arrow about 16-20" long. Exact diameter does not matter but thinner is better. Get wood file handle, Drill a hole large enough for the arrow to go in the handle ( tight fit and epoxy) leaving the arrow end with the aluminum insert in it not in the handle.
Use a 45 cal nylon brush and it will screw into the aluminum arrow insert at the end of your new custom bore cleaning tool.
Wrap a large shotgun cleaning patch around the nylon brush and then clean your chamber when done cleaning the barrel. Can also clean the raceways too with same tool and patch.
Nylon brush holds the patch, tight enough to clean any chamber yet is flexible and non scratching.
BH