Machining a swamped pistol barrel?

[Scota4570]

I am interested in a new project.  A flint pistol with a swamped octagon barrel.  I have an old , very basic, milling machine,   it is not CNC and I can not retrofit.  IT has to much backlash to avoid climb milling.  So, I have to plan my cuts carefully. 

I was thinking of making a follower on the quill that traced a swamp profile. Basically a large key pantograph.  The profile would be next to the barrel.  I would have to constantly adjust the knee.  Maybe use a dial indicator to trace the profile.  The profile could be made by springing a piece of keystock  to the degree of swamp desired. 

I horizontal mill would be better for this but I have only run one once, and not have one.  A rifle barrel could be sprung upward at the swamp.  I can not imagine a 10" pistol barrel would spring the correct amount without a permanent bend?  Could be wrong..

Anyone figure out a convenient way to do this job? 

[rich pierce]

I’d file it. Make hacksaw cuts every 1/4”. 2 strokes then 3 then 4  and so on. Rotate the flats and repeat with the cuts alternating (not meeting the cuts on the top flat). All 8 sides. Now angle grind off the bulk then switch to filing then draw filing. Nothing can go wrong.

[Jim Kibler]

As a kid, I swamped a pistol barrel by using a hacksaw to cut to depth at the small of the barrel and then used a coarse belt sander to shape down to the line and back out.  It really wasn't too hard.  A good 2x72" belt grinder would make pretty quick work of this.

A mill will be a little difficult due to the relative small radius as compared to a rifle barrel.  I've cut rifle barrels on a knee mill by just indicating in each section and then cutting.  Blend them with a file afterwards.

I think I would just grind it with the belt sander.

[smallpatch]

Wow, think I’d just buy one.

[JPK]

You can mill the taper by shimming the end up then double the shim when you have the newly milled flat on the bottom. Go nearly to the smallest part then do the same type shimming at the other end each end needing a different amount to suit your need. Then blend the waist together when draw fileing for finish. If you need the .040” taper a shim of .020” to start then .040” as you progress. Trying to bend or bow a 10” piece of barrel would be difficult at best.

[Scota4570]

Wow, think I’d just buy one.

Where? 

[rich pierce]

Rice has several.
https://ricebarrels.com/product/8-swamp-pistol-barrel-1-16-1-18-1-20-square-and-radius-groove-rifling/
https://ricebarrels.com/product/10-swamp-pistol-barrel-1-16-1-18-1-20-square-and-radius-groove-rifling/

And so on.

[Scota4570]

Thanks, great tip.  I will probably get one. 

Scot

[Pukka Bundook]

A pistol barrel being pretty short should be fairly easy to swamp by hand
I did a longrifle barrel by hand and a flat only took about a half hour, but I sweat buckets!

I took the teeth of one side of a reaper file, and bevelled  a cutting edge on it like a draw knife and used it as such.
Great long curls of steel could be cut off and had  a pile like giant sized wore wool when I was done!