The best method is to start with an oversize barrel and have it machined integral with the barrel.
What I did on my first 458 lott was to bore a piece of cr-mo tubing to the od of the barrel, then I sliced a section of the tubing ~2" long and ~1/3 the circumfrence of the tubing. I welded on a 3/8" thick piece of steel as the recoil lug, then silver soldered it in place.
I just don't like the idea of welding anything on a barrel, so long as you have enough surface area, soldering is fine.
Another slick option is a barrel band sight base with a lug welded to the bottom, and soldered in place.
I share your concern with welding on the barrel. I would wonder however, why you would silver solder and not weld. You can get less heat sink, better heat control, with a tig weld than with silver solder.
