Reaming and rifling a wrought iron barrel.

[IanH]

I have questions.

Backstory, nobody wanted the original percussion mountain rifle barrel I offered up months ago so I'm going to fix it and build a new rifle with it myself. It is wrought iron, straight octagon, 15/16"-ish across the flats, has a .336" bore at the tightest spot (middle), and lots of pitting. 7 lands and grooves. I intend to drill it out to 9mm, ream to .358-.360", and single-point rifle it by hand the old fashioned way. I will also taper and flare it because it is ridiculously heavy.

Questions are:

1. What twist for .350" PRB for mild to full power loads?
2. How many lands/grooves? A circle is difficult to divide evenly by seven, why not six or eight?
3. Has anyone ever proven any advantage to a gain twist for PRB?
4. For skelp-welded, wrought barrels, what is a good breech diameter and taper? I assume the maker felt a .33 caliber needed to be nearly an inch in diameter, but what about a .36 caliber tapered? Is it a bad idea to mill it down to 7/8" at the breech and taper down from there forward?
5. Round bottom rifling or square?
6. How deep?

My own thoughts are these:

1. One turn in 36-48", pick one.
2. Land opposing groove is traditional and seven is a good number for .32-.58, or that's how many the rifling machine happened to be made to cut. Probably makes no difference if odd or even.
3. Meh. Uniform twist works fine.
4. Ask the owl.
5. No real difference in use.
6. .008-12" per groove.

I'm not going to send it to Bobby Hoyt, he's got more important stuff to work on. I'm not going to "freshen" it with poured lead cutter guides because I have modern machine tools and want to go to a full, standard .36 caliber. If I can't slim it down some without risk, I'll buy a modern Rice match barrel; I don't want to blow myself up because I was ignorant about wrought barrel thickness requirements.

I'll document my journey with this if I can get a little help with the initial decisions.

 

[64Springer]

A tinkerers dream.

How will you rifle the barrel?

Thanks.

 

[IanH]

4' stick of 4" SCH-40 PVC with a strip of something wrapped around it like a barber pole. Pull it through a plywood plate with a hole and notch guide cut in it. Couple 2x4s, some screws, a small stick of round bar, some clamps, and a cutter head that I'll machine.

 

[Phil Coffins]

Having never rifled a barrel the odd number of grooves, I’m told, was so the single point cutter would be putting pressure on the land opposite the the groove as it cut. Your efforts may put some light on that idea. The debate on your other points have entertained many people for years!

 

[IanH]

I'm going to be using an O-1 drill rod cutter head turned, hardened, and polished to .002" under bore diameter (just enough room for heavy cutting oil film without jamming) so I doubt any traditional theory involving hickory rifling rods will be contested.

 

[Nor'Easter]

Just flagged this thread to "watch". Good luck and keep us posted. Very interested in this myself!

 

[Comfortably_Numb]

I'd use that barrel for a tomato stake and by a rice barrel. But I'm old and tired, lost my MOJO a couple years ago.

 

[Tumbledown]

For PRB, you want a slower twist. 1:66-72 is common. 1:48 works, but is a compromise for using bullets in the same gun.

 

[Comfortably_Numb]

Most all the originals had 1 twist in the length of the barrel.

 

[BJHabermehl]

I have questions.

Backstory, nobody wanted the original percussion mountain rifle barrel I offered up months ago so I'm going to fix it and build a new rifle with it myself. It is wrought iron, straight octagon, 15/16"-ish across the flats, has a .336" bore at the tightest spot (middle), and lots of pitting. 7 lands and grooves. I intend to drill it out to 9mm, ream to .358-.360", and single-point rifle it by hand the old fashioned way. I will also taper and flare it because it is ridiculously heavy.

Questions are:

1. What twist for .350" PRB for mild to full power loads?
2. How many lands/grooves? A circle is difficult to divide evenly by seven, why not six or eight?
3. Has anyone ever proven any advantage to a gain twist for PRB?
4. For skelp-welded, wrought barrels, what is a good breech diameter and taper? I assume the maker felt a .33 caliber needed to be nearly an inch in diameter, but what about a .36 caliber tapered? Is it a bad idea to mill it down to 7/8" at the breech and taper down from there forward?
5. Round bottom rifling or square?
6. How deep?

My own thoughts are these:

1. One turn in 36-48", pick one.
2. Land opposing groove is traditional and seven is a good number for .32-.58, or that's how many the rifling machine happened to be made to cut. Probably makes no difference if odd or even.
3. Meh. Uniform twist works fine.
4. Ask the owl.
5. No real difference in use.
6. .008-12" per groove.

I'm not going to send it to Bobby Hoyt, he's got more important stuff to work on. I'm not going to "freshen" it with poured lead cutter guides because I have modern machine tools and want to go to a full, standard .36 caliber. If I can't slim it down some without risk, I'll buy a modern Rice match barrel; I don't want to blow myself up because I was ignorant about wrought barrel thickness requirements.

I'll document my journey with this if I can get a little help with the initial decisions.

A lot of early rifles were 1-48 regardless of caliber. My own modern .36 cal rifle is 1-48 twist. BJH

 

[Pukka Bundook]

A twist like you mention in your OP will work fine. the smaller ball needs a faster twist than a bigger bore.
I reamed, fine bored a rifled a barrel in .45 with a 1 in 48 and it shoots fine with any load I tried it with.

The barrel you mention would open up to a .50 or more and still have plenty of meat, so you are well in at .36 or so.
Make sure you fine bore it so it's like glass before you rifle it.
And yes, as Phil says, the idea of uneven groove numbers was so the cutter ran with its back to a land.
I have rifled 6 grooves though and it worked fine.
My cutter head is wood with the cutter inserted and backed with paper.

Look forward to your progress, Ian!

 

[WALT53]

I have questions.

Backstory, nobody wanted the original percussion mountain rifle barrel I offered up months ago so I'm going to fix it and build a new rifle with it myself. It is wrought iron, straight octagon, 15/16"-ish across the flats, has a .336" bore at the tightest spot (middle), and lots of pitting. 7 lands and grooves. I intend to drill it out to 9mm, ream to .358-.360", and single-point rifle it by hand the old fashioned way. I will also taper and flare it because it is ridiculously heavy.

Questions are:

1. What twist for .350" PRB for mild to full power loads?
2. How many lands/grooves? A circle is difficult to divide evenly by seven, why not six or eight?
3. Has anyone ever proven any advantage to a gain twist for PRB?
4. For skelp-welded, wrought barrels, what is a good breech diameter and taper? I assume the maker felt a .33 caliber needed to be nearly an inch in diameter, but what about a .36 caliber tapered? Is it a bad idea to mill it down to 7/8" at the breech and taper down from there forward?
5. Round bottom rifling or square?
6. How deep?

My own thoughts are these:

1. One turn in 36-48", pick one.
2. Land opposing groove is traditional and seven is a good number for .32-.58, or that's how many the rifling machine happened to be made to cut. Probably makes no difference if odd or even.
3. Meh. Uniform twist works fine.
4. Ask the owl.
5. No real difference in use.
6. .008-12" per groove.

I'm not going to send it to Bobby Hoyt, he's got more important stuff to work on. I'm not going to "freshen" it with poured lead cutter guides because I have modern machine tools and want to go to a full, standard .36 caliber. If I can't slim it down some without risk, I'll buy a modern Rice match barrel; I don't want to blow myself up because I was ignorant about wrought barrel thickness requirements.

I'll document my journey with this if I can get a little help with the initial decisions.

I’m hoping this comes with lots of pictures it sounds really interesting.

 

[th1840]

I have questions.

Backstory, nobody wanted the original percussion mountain rifle barrel I offered up months ago so I'm going to fix it and build a new rifle with it myself. It is wrought iron, straight octagon, 15/16"-ish across the flats, has a .336" bore at the tightest spot (middle), and lots of pitting. 7 lands and grooves. I intend to drill it out to 9mm, ream to .358-.360", and single-point rifle it by hand the old fashioned way. I will also taper and flare it because it is ridiculously heavy.

Questions are:

1. What twist for .350" PRB for mild to full power loads?
2. How many lands/grooves? A circle is difficult to divide evenly by seven, why not six or eight?
3. Has anyone ever proven any advantage to a gain twist for PRB?
4. For skelp-welded, wrought barrels, what is a good breech diameter and taper? I assume the maker felt a .33 caliber needed to be nearly an inch in diameter, but what about a .36 caliber tapered? Is it a bad idea to mill it down to 7/8" at the breech and taper down from there forward?
5. Round bottom rifling or square?
6. How deep?

My own thoughts are these:

1. One turn in 36-48", pick one.
2. Land opposing groove is traditional and seven is a good number for .32-.58, or that's how many the rifling machine happened to be made to cut. Probably makes no difference if odd or even.
3. Meh. Uniform twist works fine.
4. Ask the owl.
5. No real difference in use.
6. .008-12" per groove.

I'm not going to send it to Bobby Hoyt, he's got more important stuff to work on. I'm not going to "freshen" it with poured lead cutter guides because I have modern machine tools and want to go to a full, standard .36 caliber. If I can't slim it down some without risk, I'll buy a modern Rice match barrel; I don't want to blow myself up because I was ignorant about wrought barrel thickness requirements.

I'll document my journey with this if I can get a little help with the initial decisions.

To bad I hadn't seen your add earlier, I would interested in a true wrought iron barrel. I have helped forge a few

 

[sportster73hp]

I have been contemplating this work myself. Have a 40 caliber ( i think) with a rusty bore. Will be watching your progress.

 

[davec2]

4' stick of 4" SCH-40 PVC with a strip of something wrapped around it like a barber pole. Pull it through a plywood plate with a hole and notch guide cut in it. Couple 2x4s, some screws, a small stick of round bar, some clamps, and a cutter head that I'll machine.

IanH

I have seen a guy overseas rifling a barrel in a rig like this with a twisted piece of flat stock running back and forth through a slot. He could change the twist easily by making a new strip of stock and twisting to a different pitch. I thought it was pretty clever....

 

[Pukka Bundook]

Dave,
You see the flat ribbon quite a bit in the Nordic lands.

 

[sheriff john]

Watched a friend rifle barrels with a similar "machine" made/designed by a departed but notable M/L gunsmith. Used square bar stock twisted to the desired rotation to guide the cutter. Each pass another sliver of typing paper deepened the cut. Cutting piece came out the end of the barrel smoking.

Good luck with your project. It's definitely worth doing.

 

[Sam squanch]

Were the cutters lubricated? I would think they would have to be. Oil, lard, beeswax?

 

[LongWalker]

Questions are:

1. What twist for .350" PRB for mild to full power loads?
2. How many lands/grooves? A circle is difficult to divide evenly by seven, why not six or eight?
3. Has anyone ever proven any advantage to a gain twist for PRB?
4. For skelp-welded, wrought barrels, what is a good breech diameter and taper? I assume the maker felt a .33 caliber needed to be nearly an inch in diameter, but what about a .36 caliber tapered? Is it a bad idea to mill it down to 7/8" at the breech and taper down from there forward?
5. Round bottom rifling or square?
6. How deep?

1. From what I've seen, 1:40-1:50 seem most-common in MO and OH .36-.38 caliber squirrel rifles dating 1860-1890. Sample size ~50.
2. Odd number of grooves allows the opposite land to support the cutter head.
3. I've heard some fairly-strong arguments, but seen no statistical evidence.
4. Barrel diameter like that is more a matter of what was in vogue than what the maker felt was necessary for safety. Of the wrought iron barrels I've re-bored or freshed, I wanted at least .025" of barrel wall thickness between the bottom of the rifling grooves and the bottom of the dovetails. (Are you sure the barrel is wrought iron and not a Remington barrel? Just curious.)
5. Square is easier. Also, take a look at Davenport and Day's patent #315130 for ideas on the cutterhead.
6. .008"-.010" is probably deep enough. One time I spaced off and cut rifling deeper (.021"!) it worked fine but it was a ..60+ caliber rifle.

 

[IanH]

Been cleaning up after my last gun build, almost there, now to clean the long lathe off and get set up.

I slugged the breech end and it appears the .336 bore has rifling that goes out nearly to .375", but it is difficult to measure the seven lands even with a Pi tape due to being rather irratically spaced and not cut all the same depth. I gave up, chamfered the breech, and went in about 1/4" with a 3/8" drill and it just barely cleaned up. First drill will be 3/8" then and I'll try reaming .380" and make sure all the pits get cleared out. If not, .385" it is. I have a .375" round ball mould so I'll try for .38 caliber, ish. If I have to go bigger than that I'll scrap the project and buy a Rice swamped .36 caliber barrel.

Looking at ways to make a spiral shaft rifling guide, I think it would be simpler and better to make an actual sine bar machine from scratch.