I didn't put one on a factory HB, but I sanded the channel for a Shilen 243 varmint barrel. It was probably half an hour to an hour of time with a few bits of thick dowel and various grades of sandpaper. I say "various grits, but really I roughed it in with 60 grit, started going over it with 120, and realized it was just going to be painted over and covered by the barrel anyway, so I finished it with 60. Later HB projects seemed to go faster.