heat treating

[joseph mcdonough]

hey guys just a quick question do you have to heat treat the barrels on shotguns or smoothbore guns like the trade musket or English fowler because the barrels on shotguns are pretty thin. thanks for any info

 

[WRussell]

Nope.

 

[LRB]

The only reason to do any heat treating, would be to stress relieve a barrel, which would basicly be bringing it up to an even heat overall, at or close to the point that it will not attract a magnet, then letting it slow cool. To do this right would be beyond the scope of the average gun crank. Not impossible, but few would have the means. This can also be done by cyrogenics it would seem. A stress relieved barrel, all things being otherwise equal, will generally shoot better because has better harmonics. The vibrations will be more uniform, shot to shot.

 

[George Pittelko]

At the recent Contempory Rifle Assoc show in Lexington, KY, I had a discussion with L.C.Rice on this topic of barrel stress relieving. I learned that in his barrel manufacturing process that all of his barrels are stress relieved by heating in a special furnace with controlled cooling. I'm curious what process the rifle barrel makers
follow to stress relieve barrels.

 

I believe LC is the only one currently stress relieving barrels. Could be wrong.

Just want to reiterate what Wick and Wrussell said. Don't try it. Trying to anneal a barrel is tricky business. Need very controlled conditions and most people won't even notice the difference in everyday recreational shooting. Trying to harden barrels is not a good idea. Hard generally equals brittle. In addition, heating and quenching can also cause warpage. Just bad all around.

Sean

 

[benvenuto]

1- heat barrel to upper critical temp. (800-900 deg C, or red hot) in an electric (or induction), temperature controlled furnace with a neutral gas atmosphere
2- leave barrels to cool in the furnace, perhaps over 2-4 days depending on the type of furnace

I'm not a barrel maker, but I have studied blacksmithing and heat treatment for 5 years. I wish I could say I had access to such equipment, but at college the best we have is a gas-powered muffle furnace with a 24x18x18 inch chamber... and that cost a fortune in itself, let alone one big enough for barrel treatment!

 

[Zonie]

Not only is special, large equipment required but I can see a person ruining a good barrel even if the equipment is available.

All steel that hasn't been stress relieved prior to machining, has residual stresses in it from the rolling operations which made it.
Even if the barrel is stress relieved before machining, the machining ifself will impart residual stresses into the material.
Modern rifles with the little skinny barrels they have are effected by these stresses. That is why the big buck barrels have been stress relieved and sometimes subjected to cyrogenic cycles. Those little skinny barrels need all the help they can get.

If your barrels bore is straight, it will probably stay relatively straight because the crossectional thickness of the typical muzzleloading barrel is great enough that it is not easily bent, even by the residual stresses that are in the barrels material.
If the muzzleloading barrel was stress relieved after machining, it would most likely bend to the point that it would be useless. That's why I would suggest that the whole idea is best left to lie.

By the way, even a totally stress relieved, cyrogenically treated barrel will bend enough to move the point of impact if it is left in the sun so that only one side if it heats up. Stress relieving will not help this situation because we are talking about the materials modulus of expansion which is a function of the material.
A example of this is lets say the gun was left in the sun and the right side was heated up to 150 degrees F while the left side (in the shade) only heated up to 100 degrees.
The difference of 50 degrees times the modulas of expansion (about 8.6X10E-6)times the length (42 inches) will make the right side of the barrel .018 longer than the left side. :shocking:
THAT is something that will effect where the shots go a lot more than some residual stress in the barrels material. :shocking: :shocking:

 

[JOHN L. HINNANT]

Greeting All,

As usual, Zonie has related excellant information about heat treatment of barrels, and the effect of solar heat on barrels and accuracy.

At my home range in San Antonio, Texas, I have to finish my shooting by 2:00 PM or rig a plastic tarp over the end of my shooting bench to keep the sun off of my rifle barrel.

Not only does accuracy become irratic, but point of impact (at 50 yards) will move 1 - 2 inches down. Had a fellow shooter that refused to believe that summer time sun light could heat one side of a 1" barrel enough to bend enough to be a problem.

We took my dial indicator to the range a few days later and set it up on the top flat of the muzzle. While waiting for the wind flags to settle down and other conditions to get right, the barrel warmed up enough to move the barrel 0.007 of an inch. You could actually watch the dial indicator needle move. Total movement can be as much as 0.010 inch.

If a 1 inch barrel will move like that, how much and how quick do you think a 13/16 0r 7/8 will move?

The button rifling of barrels induces tremendous stress in a barrel, be it muzzle loader or modern centerfire barrel. One famous centerfire barrel maker, anneals (stress relieves) his barrel blanks before beginning any machining operations, and then a second time at a certain point during the drilling, reaming, rifling process,

Cut rifling produces much, much less internal stress in a barrel, but is still not 100 percent stress free.

The jury is still out on Cryrogenic freezing with just about an even split among the experts and their testing. Be that as it may, Custom barrel makers void any warranty or guarantee, if one of their barrels is independently given a Cryrogenic treatment.

Specialized equipment is required to stress relieve barrels, and it is dangerous to attempt stress relieving (annealing) without this equipment and a thorough knowledge of the subject.

Again, a tip of the hat to Zonie for sound information.

Best regards and good shooting,

John L. Hinnant

 

[benvenuto]

excellent info :thumbsup:

 

[BLAHMAN]

That is really interesting knowledge, especially the dial indicator moving like it does.....I would have never given that a thought.

I wonder if that affected them old-timers wrought iron barrels as well, could have, but did they have any way to measure it, like a dial indicator?

 

Thanks Zonie. Boy, yer head has to be so big with all ,dat info youse got stored in there. yer hat size must be 11 zillion. :crackup: Really informative info. Bill

 

[Zonie]

ah thin all that larnin what's stuffed inside ma head are what's pushin ma hair out. Somethin sur is. :crackup:

 

[JOHN L. HINNANT]

Greeting BLAHMAN and All,

I would have to believe that solar reflected heat would effect an old wrought iron barrel just as much as a more modern alloy barrel. The laws of Physics apply evenly in just about all similar situations.

I once had a rebored and rifled original forge welded barrel that when hot, behaved exactly like any of my modern BP barrels.

The old time rifle makers had much practical knowledge, and I find it hard to believe they did not know about the effect of heat expanding and distorting metal. Remember, Wheel wrights were heating metals rims and shrinking them around wagon wheels for a tight fit.

Best regards and good shooting,

John L. Hinnant

If you are not an NRA Member, I am carrying your load.

 

[scott k]

I would have to believe that solar reflected heat would effect an old wrought iron barrel just as much as a more modern alloy barrel. The laws of Physics apply evenly in just about all similar situations.

It sounds like your right about this but cast iron does transfer heat nice. Like a cast iron pan. You might not get as much temp difference from one side to the other as steel.
On a side note, My first job was in a machine shop. When you work with flat stock like we did you would have to straighten back out after every machining operation.
It's amazing what happens to brass when you machine one side of it. A 12" X 5" plate might bow a 1" or more from one end to the other.
Aluminum wasn't near as bad. And cast iron doesn't move much at all.
Lehigh...

 

[JOHN L. HINNANT]

Greeting Lehigh and All,

Now here is something I really cannot give a definitive answer on.

Can you equate cast iron with dead soft wrought iron? All of my instincts say no, but I have no technical evidence to back that up.

Back in the late 1960's, when the Williamsburg Gunsmiths were working to rediscover the secrets and methods needed to forge weld barrels like the old timers, they learned that only pure soft wrought iron could be used.

Alloy metal of any kind would work up to a point, and then just collapse. The gunsmiths spent a lot of time searching out old period wrought iron for their forge welded barrels.

Alloy barrels with drilled bores were finally introduces by Remington Arms and became an overnight success. Many original old rifles were built on these Remington barrel blanks. Even some Hawken rifles have them. Hawken Shop business records confirm a number of Remington barrel blanks were purchased.



With a good barrel blank, the old timers had only to rifle the bore. Quite a time saver.

Best regards and good shooting,

John L. Hinnant

If you are not an NRA member, I am carrying your load.

 

[scott k]

Can you equate cast iron with dead soft wrought iron? All of my instincts say no, but I have no technical evidence to back that up.

John, I found this on the net. "Iron"
It's very long(79 pages) but has a lot of good info. Anwsers the question about why only wrought iron works for gun barrels.
And tells about all the kinds of iron there is.
Now I know why cast made your hands black when working with it. I Learned something today ::
Lehigh...

 

[joseph mcdonough]

guys thanks for the info but i was refering to tempering
i would think that after tempering to draw the temper like a knife. not for rifled barrels but in shotgun barrels

 

[JOHN L. HINNANT]

Greetings Ramrod Slinger,

Well shoot a mile! Just because Lehigh and I strayed a bit from your original question, you want to end all of this fun we are having with us giving a simple answer.

OK! OK! OK!

No. Do not do it. Too many bad things can happen, while only one good thing can happen.

Unless you have an existing problem, I fail to see the need to anneal or stress relieve your barrel. Not knowing the metallic composition of the barrel metal, you are already operating in the dark.

Add to this, the lack of proper equipment. It it my personal opinion, this is a disaster in the making.

No. Do not do it. If you do not trust the barrel, replace it.

Best regards and good shooting,

John L. Hinnant

If you are not an NRA Member, I am carrying your load.

 

[joseph mcdonough]

hey guys thanks for the info not doing it just asking bout it as for the topic please post away its good reading