Thought I would try out my new camera so since I was in the middle of making ramrod pipes for an underhammer pistol, I took a couple of pictures to show you what I use to hold my pipes while filing and polishing.
The 2 photos are pretty self explanatory. Using a piece of 5/16" round stock approximately 8" long, I drill a #35 hole about 2 1/2" deep. #35 is the tap drill size for a 6/32 screw. Next I make a cut about 1" in from the end at an angle. I then clearance drill this cut off piece for the 6-32 socket head cap screw. Tap the threads on the long end of the rod using a 6-32 tap. I use both a taper and a bottom tap. Slide the socket head cap screw through the end piece and then thread it into the main body.
If you leave the cap screw loose, you can rotate the thimble or pipe while filing. If you snug it up it holds the pipe firmly while you file or polish.
You can do the same thing on a 3/8" rod for 3/8" pipes. I used an 8-32 socket head cap screw for the 3/8" version.
David