I have done the odd barrel by hand.
Made a 43" barrel from real heavy drawn tubing, fine bored and rifled it 18th C way, then put flats on it and swamped it by hand.
I talked to Hershel, and he said he'd done it with a surform rasp.
Tried it but it seemed slow.
Picked up a file but soon put it down again.
Thought of an angle grinder, but figured I'd warp it.
On the wall I had an Ohio Tool Co drawknife for wood.
I tried it very gently and it would cut this pretty mild steel, so I made a 'draw knife" out of a reaper file.
Took teeth off the fine side, and ground a bevel on it and oil- stoned it to a sharp edge.
Holding this diagonal to the direction of work, (think guillotine ) I found it would tear great long shavings off that were real hot on the hands.
These shgavings looked like great thick starnds of steel wool.
I had a heap half way to my knees by the time I had that barrel octagon and flared. To be honest, a flat took about 20 minutes, but you don't need a coat on even in winter.
That barrel I left on the lower flats in its rough wavy state, and only draw-filed what showed.
Never too pictures of that work.
Have done short matchlock barrels same way.
Last one was harder steel and the chewings came off much shorter and more brittle, but it worked.
Pic of the last one, below.
Couple of pics of barrel nearer to finished;
