I got tired of the .38 build-up and now just use .357 cases - but I used a .45acp brush on a drill after letting the cylinders soak in Wipe-Out. They were clean in seconds. I have heard of the steel wool on a .38 brush and drill, as well.
I just reload 357 cases to 38 Special specs. Problem solved.
Just use 357 problem solved. I usually just soak my 686 with hopes for about 20 minutes. It normally shoots 357. Now what bugs is the discolouration at front of cylinder,I didn't believe the fellow when he told me to use an eraser , but it works.