I am working on freshing the rifling on an odd-ball original barrel I have posted about. It's "jaeger"-looking, swamped, 28.5", about .615, but has very fast twist and deep rifling (8 grooves and lands). I started freshing the rifling last night, using the quick and dirty “freshing stick” technique. The Bevel Brothers had an article on this in Muzzle Blasts in 2008. They said the gunsmith on the Lewis and Clark expedition probably used this technique, and accounts of old gunsmith shops talk about "freshing sticks". I decided to use this technique because the bore as it is right now is too rough to cast a slug and expect it to ever come out or go down. But the rifling is good enough to grip a patch and twist the rammer, so here we go.
A ramrod very close to bore diameter is made and a groove rasped around one end about 1/4" from the end. String is wrapped around the groove till it is high enough to grip the rifling. The rammer is started into the bore till it starts to stabilize and turn. Stop and make a tick mark on the rammer aligning with the front sight. Slide it in another inch and make another tick mark aligning exactly with the front sight. A line between the tick marks shows the twist. Now search for an old file or other piece of steel about the thickness of the grooves and anneal it if needed and make a cutter. Mine is about 3/4" long and about 5/16" high and made from a file. The painful part is grinding the teeth off the sides. I cut in teeth with a needle file, checked to see if they were all level, fixed that and hardened it. No tempering. Some use teeth that are just equilateral triangles but I chose to make the front edge vertical and backslope the back edge like a ripsaw. Seems to work so far. Then a mortise is let into the ramrod along the axis of the twist. Trick is getting it level and tight enough to hold the cutter securely but not split the rod when you tap it in. A rough sketch of rammer, groove for string and cutter in mortise is below.
On the driving end of the rammer, we need a handle that swivels. I drilled it for a 20 penny nail, rough cut a piece of leftover curly maple for a handle, drilled the hole in the handle a little big, stuck the nail and handle in, and that was that. Right now I'm set up to cut on the push only and take the cutter out the breech end when done, so the handle slips off easily.
Shimming the cutter is a bit tricky. I bedded the bottom of the mortise with a piece of hard stiff plastic about .040. For shims I found that scotch tape, doubled over, is about .005, same as ordinary paper, but it does not get soggy with oil. The thin shiny foil looking "brand" wrapping on the outside of plastic soda bottles is .002. I cut a lot of tiny shims of these materials. My fingers felt really big when I handle these, so now I stick them with a needle to handle them and stick them down into the mortise and tamp them into place with a matchstick.
I used the .005 shims at first when primarily cutting rust in the first groove. In the beginning there are a lot of tight and loose spots, probably pitting. I took about 4 passes with each shim, brushing off the cutter with a toothbrush and applying oil before each new pass, till it slid through without so much resistance.
Once the rust is mostly gone, resistance became greater and more even. I switched to .002 shims once I was getting real iron scrapings and it still takes 4 or 5 passes to get it smoothly cut and ready for another shim. It’s hard to see progress looking in the bore with a light cause the twist is so fast and the rifling deep, so it’s hard to follow a furrow visually.
Once I get the grooves cut deep enough to where they will really hold a slug, I’ll switch to the slug, start working from the breech, and cut the lands. I might then have to go back and deepen the grooves. Eventually I’ll have an original, big bore, fast twist, deep groove barrel that I won’t know what to do with. It may be about .63 caliber when I am done. I think I'll enjoy it no matter what; even if I have to shoot it with 40 grains to keep it from stripping a patch with that fast twist.
Or I could cut it into 3 big-bore pistol barrels!
