Mustanger
I forget -does your rifle have a patent breech-the chamber is smaller diameter than the bore size?
If so, you`ll need a brush that`s sized to fit the chamber not the bore.
Maybe if you just keep flushing it that gunk will loosen so you can clean it out.
You could get a plastic bottle of rubbing alcohol. when its empty, get some clear plastic tubing that fits the OD of the rifle`s nipple. Drill a hole in the cap,same size as the OD of the tubing. Insert tubing through the cap,so it`s just a hair above the bottom of the bottle. Then drill a very small hole in the cap.
Fill the bottle with solvent or hot soapy water, screw the to onto the bottle. attach the other end of tubing to the nipple. Wet one patch, then start running ramrod up & down.If made properly, it creates a suction action and you can see via the clear tubing,if it`s working. You`ll start seeing some dark liquid thru the tubing, -that`s GOOD -means it`s working .