Not too long ago I sent a Ruger 45 Colt and a 45 ACP cylinders to a member here to open the throats. I'm not sure what he used to do the work but they came back not so good. There were large deep gouges in the throats from his tooling. Cast bullets leaded so bad that I was about ready to send the revolver back to Ruger for new cylinders. Before doing that I purchased a 7/16" expandable lap from a machine shop supply house. I used a very fine grit lapping compound to polish out the throats. It took several hours of hand turning the lap but I eventually got most of the gouges smoothed down. I can now shoot cast bullets without leading. I also think I would have been further ahead to just use the lap in the first place and not sent the cylinders out for the throats. I guess what I'm trying to say is "live and learn".
Nighthunter