This is a little tool I made up for my current project. Wondered how the original gun was made, how the little beaded moulding lines were done originally led me to this plan.
This little tool is made up from spring steel, and hardened. The center groove I cut with a hacksaw, then rounded it with a needle file. The outside was beveled with a flat file. Saw teeth were cut with a jeweler's saw across the tool, then gashed with a triangular file. Then I bent it to the curve. Then hardened it.
It can cut a slight curve, as in forming the lines along the bottom edge of the buttstock. Or used for the long straight run of the forestock.
In practice, I marked it out shallow, then relieved the moulding on one side, smoothed up the background, then did a final pass with the riffler to fully form the bead.