All I use pre barrel clean nylon toothbrush and gun oil thrash that around the crown/thread, careful clean of the threads, clean the rifle, clean and oil thread after that
4 of my rifles have the more 18:1 chunkier thread where the others 15:1 are a lot less work to keep clean, I’ve found that say over the stay of 4 days stalking the 18:1 thread does stiffen up on remove or install on the moderator side of the thread, thats always worth a scrape off each time, they may take on more powder residue