Not to detract from this excellent tool, but a while back, one of the members here (sorry I can't remember who) posted a link to a British fellow who had a woodworking tip on how to make a quick, inexpensive "beading tool". I clicked on these two links:
Now I have made and tried a great variety of tools to aid in getting nice straight beads / moldings along ram rod channels etc.
Scratch stock :
Home made molding plane:
A beading scraper that rides a brass rod placed in the ram rod channel:
Individual form scrapers:
And I have used Acer's method of drawing a nice straight pencil line, following that with a veiner, and then straightening with a file, etc. They all work and all have their utility but all of them rely on getting the first line nice and straight. So when I saw the above links I thought, wow, that might be an easy way to get that first straight groove in place easily. So I made this very complicated tool:
And then ran it up and down the ram rod channel lips on a rifle.....like this.....
I used it first as a marking gage with just the smooth edge of the screw indenting a line in the maple. Then I turned it so that the screw slot actually cut wood. I have to tell you, that was the quickest, easiest, most sure fire way I have put a very straight groove in the forstock without fighting the grain or the natural wobble of the other tools / methods I tried.