Never fails that you always can use a third hand on doing most things in building a gun. When installing ram rod pipes, you want to hold it tight in place and drill the pin hole at the same time. I've used clamps and somehow managed to "clamp" the clamp down on my drill press base and hope all stayed in place when I drilled. Did cause for the use of a few toothpicks to fill unwanted holes though.
Recently, I added two tools to my bag and put them to use to make a great RR or even Barrel pin drilling guide.
First, I cut out five pieces of white oak to make a open ended box. (approx. 2 X 3 inches) Dovetailed the sides for strength. Doubled up the top for the turn screw threads. Then drilled and tapped two holes on the top or bottom, (whichever you like) and then make two screws out of 1/2 dowels.
Also, note that the tap and die, I use for the bottom end of powder horns.
I will make a couple of pilot holes on the side and then use my egg beater hand drill to make the pin holes. I'm also sure that this jig will come in for many other uses. (like cracking walnuts)
Took a little over an hour to make but will sure save some time down the road.