I think Rich is asking partially on my behalf as I have a "fat barrel Baby" Luger project that he and I have been discussing and the barrel band attachment is part of the process. He has really been responsible for my thinking about rekindling the project that I started probably close to 30 years ago!
Just yesterday he gave me a heads up on a "Fat Barrel" in 7.65mm that is threaded for the long receiver that I need which is being offered by Sarco. I have one ordered so we will see if that becomes part of the solution. I have done quite a bit of jewelry silver soldering years ago but I don't have the tools or ability to do the machine work for the barrel band modification.