Safe barrel wall diameter for a 58 caliber rifled barrel

[marcusb]

I have a short green rifle barrel in 58 caliber that I would like to have turned down locally. I was curious if there was any standard on barrel wall thickness for modern steels? the barrel is very large 1" and 1/8 at the breech and I would like to have as much metal as possible removed to improve balance at the muzzle. the profile will be octagon to round.

[Bob Roller]

WHAT kind of modern steel?? Some of them are not safe or certified by the mill that rolled them for barrels at all so I would forget that idea and have a custom barrel maker help you.
I know of no gunsmith or machinist that would do this without knowing what it is being turned
To do so is an invitation to disaster. WHO made the barrel you want turned down?If it was made by a company or shop still active in the trade,call them.

Bob Roller

[rich pierce]

I think from the post it's Green Mountain.  Well established.  Look at the profile of a 1863 Springfield for the lower limits of barrel diameter for a .58.

[Bob Roller]

Most, if not all these 58 caliber military rifles have a pretty hefty breech and bolster arrangement. The thin part is near the muzzle where it belongs. I used a one inch GM 58 caliber barrel on a flintlock rifle I made and I think it had about .200 wall thickness which was OK because of the material the barrel was made from and the fact that I do not pour half a horn of powder down it every time I load it.

Bob Roller

[Don Getz]

I sure hope that machine shop knows what they are doing.   What you are asking them to do is not an easy thing.  To
get a good octagon to round barrel, the octagon portion should also be tapered.   Also, to turn a full octagon barrel you
cannot just put both ends on centers and start turning, this will only end in a disaster.   If that machine shop charges
what most machine shop do, you will end up with a very expensive barrel, and in the end it probably won't be right.  You
will have to give them a drawing, with dimensions, of how you want it turned.   Are you prepared to do that?   I would
suggest that you sell that barrel and then buy an octagon to round barrel from a reputable barrel maker..........Don

[marcusb]

Thanks for the input guys. It is a 28" Green mountian barrel someone had cut down I got for a good price. The breech is still octagon but they had tried to draw file the taper and discovered that Green Mountain does not use leaded steel!!! To keep costs low I was just hoping to have a straight taper round to the muzzle after the octagon section, hence the safe diameter measurment, which would be the muzzle diameter.

[Jerry V Lape]

The smart guys already did provide good answer.  Use it as is or pass it along to someone who will. 

[Dphariss]

I have a short green rifle barrel in 58 caliber that I would like to have turned down locally. I was curious if there was any standard on barrel wall thickness for modern steels? the barrel is very large 1" and 1/8 at the breech and I would like to have as much metal as possible removed to improve balance at the muzzle. the profile will be octagon to round.

There are other considerations in ML barrels than pure wall thickness. Things are often threaded into them for example.
1137 is a steel that may work harden if the barrel is too thin at the breech. But its not likely a rifle barrel would be made this thin.
I would leave it full size at the breech and have it machined octagonal, with flood coolant, to 1" at the muzzle. I would not turn it 1/2 octagonal in any event. This makes for a stress riser at the point where the octagonal section ends.
Making the muzzle small and leaving the breech end untapered with result in the need for a very high front sight.
If its too heavy the best solution is to sell it and buy a lighter barrel 1" then straight taper it to 7/8" at the muzzle.

Dan

[marcusb]

Hmmm, intresting responses, some I had not expected. I have no problems supplying drawings, I have done both board and the current autocad fancy stuff. I basically was approaching this project form a cost standpoint, thinking a pistol barrel would not be a tremendous undertaking, perhaps I was wrong. Heres another angle, what about boring it to a larger caliber smoothbore? I would be happy with something in the 60's smooth. Any ideas how this could be done at home with shop tools?

[Ted Kramer]

I'd estimate that by the time you have any of the operations mentioned performed- turning forward section to tapered round, machining it to tapered octagon or boring to .60+ smooth bore- you'll have as much or maybe more money tied up in it than a new barrel of the configuration you want will cost. Just my opinion.
Ted K.

[Roger Fisher]

If she ain't broke don't fix her

[Dphariss]

One other point.
"Moderns" are FAR too concerned with lightness and "balance".
A short 1 1/8" 58 would make a great hunting rifle and not that heavy.
But if its expected to balance like a Purdey there will be a level of disappointment. Traditional American rifles did not handle like shotguns, this was generally the case well into the 1890s and the advent on modern HV smallbores.
If you have a lathe and can make a piloted reamer its possible to ream the bore then ream it with a straight bit if needed and/or polish it. But this may require some previous experience for success.
But then you have a smoothbore with the weight of the rifle but not the utility.
Sell the barrel to someone and buy one that will fill your need. It will save a lot of work and head scratching.
Having a machine shop do a one off job is never cheap. 
Dan