I use TC's bore cleaner. It has worked excellent so far. I simply take out the breech plug, run tons of wet patches and then push dry patches through until they come sparkly clean. Then I clean the breech plug threads, clean the breech plug(throw it in a container of soapy water and scrub it), put grease on the breech plug, and reassemble and oil everything or use bore butter. No rust or problems so far with that method.

Hope I helped.