I picked up an original smoothbore barrel years ago. The bore was rough but it is a stout round barrel about 36” long and was about 16 gauge more or less. In its latest iteration it was a percussion halfstock, based on the attached rib. I scrubbed it inside as best I could and it looked salvageable with a couple crawdad holes about a foot from the breech plus pitting throughout and the usual breech end erosion.
Step 1 was to cut an inch off the breech and have a friend face it and thread it for a 7/8” breechplug on a lathe. We had to cut it from the breech because the breechplug and drum section was not worth trying to salvage. When trying to restore and original barrel to working order, one needs to decide whether cutting a section off each end will be most efficient, and if one can use a barrel shortened in this way. I have plans for an English cavalry carbine.
Next step was to ream the bore until all rust was gone, and the true extent of pitting could be assessed.
I used an adjustable reamer, with a range of 21/32 to 23/32”. It has a square end. To use it my buddy set me up with a piece of mild steel square tubing that fit the end of tge reamer, and a handle that would slide on the tubing and could be tightened with a set screw.
Then I mounted the barrel in a vise and at the end of the workbench mounted a vertical pine board with a round hole in it the square tubing would just pass through. It’s a very temporary, shade tree mechanic setup to align the reamer to the bore as the work is done. One day I will set up an actual boring bench.
I set the reamer to just hit the high spots and hand turned it, advancing about 1/16” per turn. After about 8 passes while increasing the cutting diameter of the reamer, the rust was gone and it looked like I could get it clean end to end. After another 8 hours or so of cutting, cleaning the reamer, swabbing the barrel, adjusting the reamer, and repeating, it is shining like a mirror. It’s now about a 12 gauge barrel. I don’t advise this as an economic practice. For me it’s another skill set box I can check.
