I found an outstanding solution!!!
Fellas, I was tinkering the garage last weekend and started looking around at what I had around that I could try to remove the burn marks. "Cameo" copper,brass, porcelain cleaner! I use it to clean the really dirty brass that my tumbler can't clean, like the cases that have been buried at the range for the last few years. It's a powder, I started by snaggin' one of my wifes useless tiny tupperware containers and dumped about a tablespoon of power in it. I diluted it w/a small amout of water to make a watery paste. I used a q-tip to apply in the cylinder and the forward part of the cylinder where the burn rings were. With 3-5 minutes of letting the paste dry, I wiped it all out and it looked as if it was brand new again. A 10. oz container of this stuff goes a long way compared to the other stuff I tried, and it's much cheaper. I keep the paste in a closed container for later use. If it's hardened, I just add a bit more water. This works great for me and you may like the results just as well. Mind you, my S&W mod 649 is stainless, I don't know if this will damage any other surface. My 2. Bill