Came out looking great!
I made a couple "nested bead" front sights for shotguns that I cut down for Cowboy Action Shooting using basically this same method. Instead of the bead torquing down against the barrel, I'd screw a brass or stainless nut onto the threads and let the bead "nest" into that, and turn the screw and nut in the drill against the file and stones to turn down the diameter of the nut. Left a nice round ball bead nesting into a silver or brass ring. Adds a bit of height to the bead.
We just did a "sawed off 500" this winter with my brother-in-law. He found a deal on a used mossy that was cheaper than getting another barrel for his old 500, so he bought it and we cut it down. It's a vent rib, so we had to resolder (low temp to preserve the bluing a little) the rib, then D&T for a brass bead. Hindsight 20/20 we should have used high temp solder, since he just ended up doing a krylon job on top anyway!