Alright this is one of Dad's guns. He first marked out and filed in the band into the barrel, looks like it was done on the lathe but it wasn't. The he cut out the groove for the silver and under cut the steel a bit. Now you can either create a whole bunch of small teeth, in random order and different directions, in the groove, or use solder. To create teeth just use a small square graver. If you use soft solder you better have a great fit or make sure that the solder matches because it will show. The pure silver will be soft enough to conform around the teeth and into the uder cut area when tapped or beaten in. Either way you then clean up with a file.