I have a newish S&W Model 21 that leaded furiously. I was using the same bullets as I use for .44 Magnum in a couple of 629s that hardly leaded at all and what there was of it would come out with a few brush strokes. Inspecting the bore, it looked like it had been rifled with a tool made from a broken nail file. The forcing cone was actually stepped! And the throats measured correctly for jacketed, but not for lead, bullets.
First off I ordered a throat reamer from Brownells in the right diameter and opened them up a tad. I did not hone the throats. The result was less build-up in the throats and perhaps a little less in the cone. I had also ordered a forcing cone reamer, but if I were to use it, the length of the cone would be pretty long, so I let that go.
I did buy some of those hot lapping bullets in the range of grades and followed the directions, loading slow, cleaning thoroughly between grade changes, etc. The results of that were a nice shiny bore that looked as if it had been originally cut with a broken nail file. But now shiny! And lead didn't stick nearly as hard.
It still leads, but not so bad. I've never found a combination of revolver and lead bullet that doesn't lead. I have found some that are better or worse and some that clean easier. The old wisdom of going harder to prevent leading has been replaced with the opposite. If you cast your own, experiment. The other thing I found is that despite any advice you might hear about using nylon brushes instead of bronze, the time you waste using nylon and gallons of solvent and muscle is worth saving even if you have to get a new barrel at 50,000 rounds instead of 100,000 rounds. But I'm never gonna get to 50,000 rounds on any of my handguns anyway. (Nylon might be better for match rifles. Those shooters have all kinds of superstitions, and some of those may actually have merit.)
-Don
