I am having a new Shilen S/S match barrel put onto my '06. The profile of the barrel is much heavier than I wanted (we won't even go into this)and the 'smith has undertaken to re-profile the barrel to the shape/weight that I want.
It will not require radical lathe work. Essentially he is bringing the barrel which is a #6 profile down to fractionally slimmer than #5.

Will this create stress problems since Shilen de-stress all their match stuff after cutting according to their web site?

500 Nitro---

Yes, It WILL introduce stress in the barrel......what effect it might have is not predictable.

Thanks J,
would you suggest that it is left as is?
It makes for a pretty heavy hunting rifle.

500Nitro--

If it were mine I'd re-order and try to sell the one you have.

Of all the variables in a custom rifle I feel the barrel contour is as important as choosing the action. The barrel truly makes a BIG difference.

I once built a rifle with too heavy a barrel and ended up taking it back and building the customer another rifle.......that was the LAST time I ever chose a barrel for the customer.

Shilen, Pac-Nor, and probably most other button barrel makers stress relieve the barrel after rifling, but before contouring. When an order comes in they can just grab a blank off the shelf, contour it to whatever contour is needed, and then ship the barrel. They do not stress relieve again after the contouring. You are not going to hurt a properly stress relieved barrel by taking it from a #6 to a #5. I have asked Shilen about this very thing as I do all my own contouring.

Hope that helps,
John

[ 04-16-2003, 00:39: Message edited by: gasgunner ]

I'll go with gasgunner on this one. I contour or recontour most of the barrels I use and never see any problem with any of the good modern barrels. I recall some Bauskas that moved around a lot and one Ackley barrel that would near crawl out of the lathe with each cut. It is seldom that one moves now though.
My best shooting BR barrels were Harts that I tapered to LV contour from a 1 1/4 inch blank. Maybe just coincidental but I taper all barrels for my own target rifles since. Regards, Bill.

Can a button rifled barrel be rebored?
I once thought about having a muzzle loader barrel rebored, and a gunsmith told me it wasn't reasonable because of the stresses set up in the rifling process.

Any experience? Thanks.

Jerry

I don't know if it true, but a gunmsith I know tells me that one difference between expensive and cheap barrels is how many are thrown out when they warp from being turned down.

I got a barrel from Midway that is bent 1/2".

I am suspicious that my Lothar Walthar barrel shoots so well when hot is that it was stress relieved better than my other barrels.

I have a barrels I would like to turn down, but I afraid they would warp. Yeah, I know they are stress relieved, but it can't be perfect stress relief.

JerryM, it depends on what kind of metal the barrel is made from. If it is the true traditional muzzleloader soft unhardened steel, it can be rebored and rerifled without too much fear about warping. If it is a harder, more modern alloy, then it could warp when rebored. Tendency to warping will be worse if the present bore is not perfectly centered.

[ 04-19-2003, 23:30: Message edited by: eldeguello ]

You did not mention the way your barrel has been rifled, hammer forged,button, or cut. What type of stainless steel? What type of heat treatment has the barrel been through and at what stage of manufacture. To give an accurate answer these variables must be considered. Any machine work performed on a finished part will induce stress into the metal. Generally barrels are stress relieved after finish rifling, leaving the barrel in a blank configuration. Contouring, threading, chambering and crowning are all performed after stress relieving, this machining creates a certain amount of stress. Machining techniques used during this final stage of barrel completion will have a direct affect on the amount of stress within the metal. The stress in your barrel will be in direct relation to the variables mentioned above and the skill of the machinist performing the additional machining.

The stresses are supposedly set up in the rifling process.

Maybe you don't know how fast I can shoot a ML. Repeat shots are often under a minute if I am well prepared. I admit I would hate to have been fighting Indians in the days of ML with my skill. I would not have any hair to show.

Jerry

The tendancy of steel to warp when turned is due to the cutting action relieving stress, rather than inducing it. If a barrel is properly stress relieved to begin with, you won't hurt it by recontouring it......if it wasn't, it was already a cull. I once asked a well known barrel maker in my area if it would hurt to recontour one of his barrels. He replied @#%%$#*@..it didn't hurt the
*&^%$# thing when I contoured it the first time did it???? I took his advice to heart, and have recontoured several barrels since with no ill effects.
David

What process do barrel makers use to relieve stress? Would it be possible/practical to recontour a barrel and put it through this process again?

Is this where cryogenics comes in? Would recontouring followed by a cryo treatment take care of any concerns about stress induced by the recontouring?

That's a lot of questions!!!

TIA,
Bob

That is correct DBB, if the proper machining techniques are used then the stress induced into the metal will be minimal. However, if during machining tooling is dull, clamping is improper,or excessive heat is generated even with stress relieving you will create stress that in return will allow the metal to warp.
Hope this helps

The most basic form of stress relieving (mechanical) would be to beat the darn thing repeatedly with a hammer!!Not very practical, so the next would be shot peining (still just fancy hammering)
Most barrel makers will follow the procedures recommended by their barrel steel supplier, usually a controlled heating and cooling procedure,Before they contour. If they contoured first, the thing would be as crooked as a snake's track. This is especially true on CM barrels, but also SS.

I had one Shilen SS barrel last year that simply refused to shoot, so it was returned. Shilen gaged it, and scoped it, and could find nothing wrong. So they replaced it. So far, so good. They also re-treated the original barrel and returned it to us NC with a note of explanation, and asked us to try it again. It looked like shit, all discolored from heat.....even the bore.....but it shot great!!

http://www.bsu.edu/web/mdmcclellan/gunbarrels.html#LOTHAR

"Match Barrels
Lothar Walther match barrels are given an additional treatment to achieve the highest possible quality.
By heat-treating the material to red-heat, 'low tension' is achieved. During this important process the barrel is heated for an exact duration of time and then allowed to cool slowly to room temperature in the
oven. Here, the time duration plays an important part. Only when the barrel is heated long enough to the optimal temperature for the respective material composition does it lose its tension. Appropriate slow cooling to room temperature is necessary to prevent tension building up. After finishing the barrel contour and fitting the cartridge chamber, each barrel is once again individually fine-polished to achieve the best possible inner surface."

Go to the link below and click on the April issue and read the article by Bill Calfee. He discusses the effect of contouring a rifle blank after button rifling and how it will result in an increase in the bore diameter. With a normal contour, where the muzzle diameter is smaller then the rest of the barrel, the bore at the muzzle tends to be looser, not what one wants for accuracy. As I understand it, it is a must that all button rifled barrels be lapped after contouring and before crowning. Your Shilen barrel is button rifled. Since it is disadvantagous to lap a finished barrel, due to the possibility to damage the throat and crown, you won't be able to lap your barrel again after re-contouring.

http://www.precisionshooting.com/

[ 04-25-2003, 23:33: Message edited by: B B ]

The stress relieving that is done to the barrel (prior to contouring)is done to eliminate the stresses that might cause the barrel to grow from turning. The best shooting BR barrels I have had have all been barrels which I turned from a 1 1/4" blank. They must have been OK.I have seen no evidence of growth in internal diameter in any of the match grde barrels.
I asked one barrelmaker about this about 25 years ago and he said the barrels would lose their paralellism after tapering. "How much?", I asked.
"don't know".
"Have you gauged one before and after tapering?"
"Well... no".
I was never able to measure any change in any of the pieces of SS match grade barrels I tried it on. I am fairly capable in the use of hand measuring tools and would have been able to measure .0001". I turned pieces from 1 1/4" down to .700 to measure. Interestingly enough I was able to measure change in some cut rifled peices which had not been properly stress relieved.
In machining hydraulic cylinders, we used material which was drawn on a mandrel (designated DOM). This stuff would grow significantly when the outside was turned down. If the material was stress relieved before machining growth was often non existent and always minimal. Since internal diameters were between 4 and 8 inches, growth was easy to measure.
Over the years I have turned blanks down as far as .550 at the muzzle with no apparent ill effects so it's not something I worry about. Regards, Bill.