Barrel straightening

[oldred]

Goodsteel, while machining a Green Mountain 1.270" round blank into the heavy octagon barrel for my High Wall I was amazed at the ease with which even a heavy barrel can be deflected. With about 3/4 of this 32" barrel extending past the steady rest on my lathe I had my dial indicator set up at the muzzle and by gently pushing with my finger tips I could get .020 to .030 deflection with almost no effort at all! It's no wonder the wood in a stock has such a profound effect on accuracy.

As far as barrels being bent what really matters is the sight alignment with the bullet trajectory, theoretically a barrel could be shaped like a pretzel and shoot straight if the sights were aligned with the path of trajectory after the bullet leaves the muzzle, but of course a large bend creates more problems that just sight alignment.

[MBTcustom]

Goodsteel, while machining a Green Mountain 1.270" round blank into the heavy octagon barrel for my High Wall I was amazed at the ease with which even a heavy barrel can be deflected. With about 3/4 of this 32" barrel extending past the steady rest on my lathe I had my dial indicator set up at the muzzle and by gently pushing with my finger tips I could get .020 to .030 deflection with almost no effort at all!

That's true old red. Now, set up a barrel in your steady rest spider only, so that it is rigid enough that you could machine it if it were attached to the chuck side spider. Now, run an indicator mounted in the chuck, and tell me how close you are to zero.
Huh? the spider itself wants to steer the barrel off center? you dont say?
Now observe how much pressure it takes to bring the other end of the barrel into alignment with the chuck.
Quite a bit of pressure is required in spite of the fact that your spider bolts are just barely snug enough to be rigid.
SO when you set a barrel up between two spiders, weather they are on iether side of the headstock, or on the steady rest, you are inducing longitudinal stresses into the barrel.
How likely do you think it is that the barrel is actually running strait?
It aint got a snowball's chance in hell.

That's why I spent a lot of time developing spiders that can be "aimed". When I set up a barrel in the lathe, the only way it could run truer, is if you put it in a zero gravity environment and give it a spin, and the straightness is preserved through the process of threading, chambering and crowning.

Because of this, I can tell if a barrel is truly straight. If I am working with a competition barrel, I send it back if I can detect any bend in the pipe.
that being said, it is not very common for me to find a straight barrel on any of the major manufacturers factory rifles.

[platinumtp]

I have a Winchester Model 1873 with a bent barrel. Will Savage repair it? If no, then who?

[oldred]

What are you calling "bent"? Is really bent to the point it can be seen? Is it REALLY bent as in a severe bend over a small radius?

[johnson1942]

just saw your post and want to do some input. many barrels are straightened. however the memory of the bend is in the steel. when the barrel heats up after a few rounds it starts to travel again toward the bend it has in its memory. impossibe to keep it from walking on the groups. however their is a cure. saw many a gun cured of walking groups with one 70 dollar cryo treatment. the steel looses the bent barrel memory when cryotreated. i use cryo plus on the internet, she is cheap and just as good as the others. after you straighten the barrel, cryo it. you could also sonic stress relieve it but that would cost much more. you would be surprised at how many factory over the counter guns have barrels made from straighted bent bar stock. thats why some well made factory guns wont shoot for ****. a simple cryo treatment cures it.

[bannor]

that is great to know, man. I've always just assumed that a bent barrel was scrap metal.

[johnson1942]

i had a friend years ago who lived 1/2 mile south of the canadian border in the heavy woods. all his red meat came from the wildlife their. he bought a 300 weatherby mag. it would hit dead center the first shot then walk right off the target at 200 yards. it drove him nuts. it was a well made gun with a well made barrel but the barrel had the memory of a bent bar stock before becomeing a well made barrel. after he cryo/d the barrel it shot dead center at 200 yards, round after round their after. it took the memory of the bend out and is now a very special gun. the steel in a cryo/d barrel will last longer then one that isnt also. we never chronographed his loads but usually they shoot faster after cryoing as the steel is slicker or the carbon in it is. the barrel harmonics become a lot more quieter and consistant in a tighter circle on the muzzle after cryoing also. its a win win thing to do.

[Multigunner]

Something I remember from a thread on 1903 replacement barrels.
Some of the barrels turned out to have been demilled by bending before being sold off as scrap metal.
Someone bought up a bunch of these barrels and straightened them then sold them as NOS without alerting buyers to the salvage methods.

The barrels appear to have been reasonably serviceable, but when they had straightened the bend the method they used caused the bore to oval at the point of the bend. This would not be a favorable condition.

[DeanWinchester]

The last machine shop I worked in had a hydraulic press specially made for straightening lead screws and linear guides. It had a dial indicator and you could adjust the stroke by as little as a half thousandth. In the hands of an experienced operator it was very good at straightening anything. I straightened a Garand op rod on it while worked there. Wasn't exactly National Match quality but the rifle ran fine after I straightened the part that was bent.

It CAN be done but as said before it ain't for any ole body.

Hey Goodsteel, if your lathe is big enough; I've straightened tubing on a LeBlonde Makino lathe years ago by finding the high spot and using the tool post to put pressure on the high spot. (NOT WHILE ITS RUNNING OBVIOUSLY). Use an end mill to cut an appropriate radius in a piece of square stock and put it in the tool post. You need a very sturdy carriage to do this though.

[country gent]

Federal made a bed with 2 centers ( think 2 tailstocks) and a screw press that was adjustable its length of the bed. It was very solid casting on the bed and ways were ground for accuracy. An indicator on stand could be positioned on bed on unders side of the srew press. and these were made for straightening bars and or tubes. With the fine acme thread and big hand wheel a lot of controlled force could be applied to straighten a part. I believe there was a set of tailstocks with vee blocks instead of spindles/centers also. We used them to straighten work before od grinding. Looking thru a barrel at a distant cross wire can give a good idea of how straight and or true the bore is. A bore that isnt straight or bent appears oval when looking thru it at the cross. It dosnt show internall stresses in the stock. I believe that is why a rifle may perform better with age and or time, As metal ages stresses are relieved naturally from temperature changes and atmosperic changes. Cruro speeds these changes up as does the sonic stress relief. We had a "super freezer" at the last shop I worked (60* below zero) when making some gages or tooling ( vee blocks, angle plates, straight edges) we would give a weeks cycling of out of freezer when you came in into freezer before going home for 5-7 days. It helped to relieve stress and made grinding into tight tolerences easier. Krigers barrel stock is cryroed before starting to ease machining I was told.