What do you use as a de-leader?
I usually get a little leading in bore and chambers. I usually end up shooting about twenty-five rounds of jacketed stuff to remove the bulk of the leading. If I have a leaded bore, I soak it in Hoppe's #9 for a few minutes, then scrub my bore with Hoppe's on a stainless steel bore brush. Followed by dry patches, this takes care of my leading problem. For the chambers, I soak with Hoppe's #9, then brush with an oversized bronze bore brush (i.e. Use a .50 caliber for .44 and .45) chucked in an electric drill. I have a short section of old cleaning rod for this.
For removing carbon, I use automotive carburator cleaner and flannel patches.
I know most folks shy away from stainless steel bore brushes, But I've used them many years now with no ill effects. Use Hoppe's #9 or WD-40 for lubricant, and pass the brush all the way through the bore.