All ML cleaning-patching should see an outer, front-to-back wrap versus a side-to-side wrap. Patches 2-1/2 to 3 incheswork best in 50-58-cal rifles - either round or sqauare... doesn't matter.I commonly double & triple wrap my patches to get the bottom of the my sidelocks boreclean. When I'm down there, I twist & turn the ramrod clockwise a few revolutions & sometimes surprised by the fouling I capture.

There are a variety of ramrod attachments you can try - to see what works best in your ML. Choose from bore brushes, jags, scrapers, patch removers, aero-tip bullet seaters,& ramrod thread adapters.

One of them will likely work nicely at the bottom of your bore. Be sure to include some liquid solvent either poured-in or sprayed heavily prior to cleaning the breech-bottom.