My 627 has a removable port. I've had pretty good luck taking the thing off, putting it in a small plastic screw top bottle with some kroil, and putting it in my vibrating tumbler. Knocks a whole lot of the lead out.
I get most of the rest with a sharpened brass cleaning rod, the ones for pistols.
They're a pain in the rear with cast bullets, but they sure make that follow up shot quicker.