Unbending an old barrel

jkipp85

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So I have a very unique Swiss antique (actually, not legally) rifle that ended up having a rather defined bend 1/2 down the barrel after I shot a few of my antique-purpose reloads for it (Swiss GP90 reloads, low power, long bullet). I honestly don't think this bend was there when I bought as it was fairly obvious looking down the barrel at the range. Perhaps old metal fatigue?

Without going into too many embarrassing details it's now not-perfectly unbent, but I want to explore options if possible for a gunsmith or machinist to so something a little more professional for this old girl. Even if she never shoots again I want that bore nice and straight. I've seen a short video with what looks like large rollers and a metal lathe set up for straightening.

Does anyone have any experience or recommendations for something like this?

I would imagine having a NEW barrel made would be prohibitively expensive but I'm open to it.

Thank you all.
 
It's not a lathe, it is a specialized hydraulic press. I use to streighten all sorts of things from gun barrels to pistons to parts for CNC machines. Some of the old school gun manufactures still do it by eye but lazers and digital gauges will give you the best results. BTW, the straightening process is just for the exterior circumference.
 
So I have a very unique Swiss antique (actually, not legally) rifle that ended up having a rather defined bend 1/2 down the barrel after I shot a few of my antique-purpose reloads for it (Swiss GP90 reloads, low power, long bullet). I honestly don't think this bend was there when I bought as it was fairly obvious looking down the barrel at the range. Perhaps old metal fatigue?

Without going into too many embarrassing details it's now not-perfectly unbent, but I want to explore options if possible for a gunsmith or machinist to so something a little more professional for this old girl. Even if she never shoots again I want that bore nice and straight. I've seen a short video with what looks like large rollers and a metal lathe set up for straightening.

Does anyone have any experience or recommendations for something like this?

I would imagine having a NEW barrel made would be prohibitively expensive but I'm open to it.

Thank you all.

Doubtful that shooting it caused the issue. The bend was very likely there before you purchased it.
 
Bevan King once gave me a short lesson on straightening a barrel - but sadly I didn’t retain nearly enough of the details.... If I remember right he plugged the far end with a plug that had a very small hole, and you had to read the internal shadows. I can’t remember how or even if this is right.

I would call some of the older barrel makers and ask for advice.
 
you pretty well have it right DG
.,plug that fits bore from muzzle with a #30 hole and a case from the chamber side with the primer removed .Then put it in the barrel straightener with the dark shadow on the single leg and tweak till all shadows disappear from looking through both ends .
just small adjustments ,lots of small adjustment and then some more .he straightened a barrel once with a easy to see bend to straight took a bit of time and finish was not affected
 
Doubtful that shooting it caused the issue. The bend was very likely there before you purchased it.

Yep. Fatigue doesn't mysteriously bend stuff. It was bent before, or got bent somehow since it came home.

In a barrel shop that could have a skilled tradesman using it, a fly press built for the purpose would make sense. For the rest of us, I think a small hydraulic press seems a more attainable goal.

Some copper or brass pads, a set of rollers to spin the barrel on while it is being looked through, and of course, the sense to see cause and effect, while using the rest of the tools, would round things out. Even a flat surface to roll the barrel along, can tell you a lot about how straight at least the outside is.

Well worth keeping in mind that not all barrels are truly straight, or in the centre of the bar they started out as.
 
OP, a couple or so years ago I had a rifle brought to me with a bent barrel. It had met a tree while in the gun grabbers on the front of a quad. Not my rifle but a guy I know and he had at some point borrowed the rifle and damaged it. Turns out it was one of his dad's favorite rifles. So for a few years it sat, bent and useless but otherwise, a very nice rifle.
I think it was member louthepou? or someone from here, assisted in getting the rifle to Jason Spencer at Gunco. I was truly amazed at the end result as I figured a new barrel was the only solution to a bend like that. The rifle shot wonderfully afterwards and the old fella got kinda emotional when i returned it to him.
The cost was so miniscule that I was also very surprised.
 
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The old barrel maker from Alb. Ron Smith showed me how to spot a bent barrel and he didn't use any bore plugs with holes in them, he stood in the shadows in his shop and looked down the bore of the barrel at a bright sunlit window. On a perfectly straight barrel the bright halo ring inside the bore will be perfectly round, if the barrel is bent the halo will be oblong...the more curve the more pronounced the football shaped halo. He had some reject barrels in a pail there that he used to prove the method...you could very easily spot a very slight bend after looking thru his specimens.
 
Bevan King once gave me a short lesson on straightening a barrel - but sadly I didn’t retain nearly enough of the details.... If I remember right he plugged the far end with a plug that had a very small hole, and you had to read the internal shadows. I can’t remember how or even if this is right.

I would call some of the older barrel makers and ask for advice.

I was taught how to see if a barrel was straight back in 1966 from my first gunsmithing instructor (Bill Prator) at Trinidad Gunsmithing School.

I hold the barrel and point it at the floor. Some barrels you can look through with your eye very close to the barrel and see concentric rings just like on a target. If the rings are concentric the barrel is straight. If the rings are hard to see reducing the hole in the far end by use of a plug with a small hole in it will accentuate the visibility. You can bend the barrel by hand easily and see the rings distort.

This is a hard picture to take, it is the best I could do...

bore.jpg
 
OP, a couple or so years ago I had a rifle brought to me with a bent barrel. It had met a tree while in the gun grabbers on the front of a quad. Not my rifle but a guy I know and he had at some point borrowed the rifle and damaged it. Turns out it was one of his dad's favorite rifles. So for a few years it sat, bent and useless but otherwise, a very nice rifle.
I think it was member louthepou? or someone from here, assisted in getting the rifle to Jason Spencer at Gunco. I was truly amazed at the end result as I figured a new barrel was the only solution to a bend like that. The rifle shot wonderfully afterwards and the old fella got kinda emotional when i returned it to him.
The cost was so miniscule that I was also very surprised.

Interesting that you should mention Jason at Gunco as that was the first guy that came to mind when I started reading this thread.

He learned rifle smithing/building from one of the best old world trained smiths.
 
Where does your bent rifle shoot? Way off from what the sights allow? If you can sight it in it doesn't really matter if the bore is straight or not.
 
At the risk of sounding out of line... is there no go-to guys in the modern day era? One gun shop turned me away almost laughing about my luck.

Here's the link the lathe operation

https://youtu.be/urLG3m5lGlk

I watched that video through a couple times, and for the life of me, can not really tell what they were trying to accomplish besides showing the barrel spinning in the lathe. Zero knowledge to be gained there.

Not too surprised at the laughter. lots of shops are barely able to mount scopes on site, and farm out work.

Guntech hits on another good point, if it shoots well, don't mess with it. Feinwerkbau, a German maker of among other things, Olympic level air pistols, once made a pistol that had the barrel loop completely around the air cylinder, and it shot as well as their other guns.It was arranged sort of like having the rifle barrel doing a wrap around the fore end before ending up where a rifle barrel is expected to point.

Lesse....
feinwerkbau2.jpg


If it shoots OK, don't #### with it.

Otherwise, I still say the small hydraulic press is a good bet and do it yourself. Some copper pipe smacked flat will make adequate pads that wont leave marks on the steel, and the rest is pretty much reliant upon your ability to observe, and react to what you see happen when you apply some pressure.

Brownell's used to (maybe still do) sell a barrel straightening tool that was a steel bar with two hooks or loops that went on either side of the bend, and a bolt that you turned to press on the bent section of barrel, Theirs was aimed at shotgun barrels, but the idea is one to look at too.
 
Where does your bent rifle shoot? Way off from what the sights allow? If you can sight it in it doesn't really matter if the bore is straight or not.

There is only one fly in that ointment.

The rifle will only shoot to point of aim at specific distances.

I've tried this on several rifles with bent barrels. Of course, it depends on how bad the bend is. A slight bend may hardly be noticeable out to 100 yards but will definitely drift where the bend deflects as distance increases.

I had a 338-06 fitted with a take off barrel. No, I didn't do the work, it came in a trade. That rifle would shoot to point of aim at the distance it was sighted in for with moa groups.

When the distance was increased from 100 yards to 300 yards, the group was 8 inches off point of aim at 2 o'clock high. It increased that POI as ranges extended.

I tried several things, such as load development, bedding, re mounting scope bases, rings and exchanging scopes before doing what I should have done in the first place, check the barrel for straightness.

There was a barely detectable offset in the rings as your good pics show.

The only thing I can assume is the barrel was over heated when it was being profiled. Very difficult to see.

I went to a friend with the rifle and showed him the issue. We pulled the barrel and chucked it up in his lathe and set up a dial indicating plunger micrometer to see if we could measure the bend at its central point and of course to find that point. If memory serves, it was around .008 inches. Not much but enough to give issues.

We marked the top dead center of the bend and took it to a hydraulic press, where we applied force to bend it back. Then back to the lathe. NADA. The bend hadn't changed at all.

Back to the press, more force, but instead of pressing it to zero, we pressed it beyond zero to the same amount as the bend. Then back to the lathe. It worked, but not quite enough and we had to repeat the process a couple of times until we were satisfied. It came out very close to zero.

Barrel steel is flexible.

That rifle shot acceptably out to 400 yards, where I quit testing it. It consistently shot under 1.5 moa to that distance with hand loads. No matter how hard we tried, that was the best it would do with the loads it liked. That rifle is still shooting Elk and Moose on a regular basis in Ft St John region. It gets less than 50 rounds per year shot through it and its present owner says he hasn't done anything but clean it and make sure its shooting to point of aim out to the distances he's comfortable shooting.

Here's the caveat to getting a barrel straightened. It can get expensive if there is a lot of shipping involved and the gunsmith is on a learning curve. I'm sure guntech has the necessary experience to do the work.

Whether he's still willing to do this sort of work????

Then, there is another problem that might occur. IF the shooter is one of those that likes to shoot without allowing the barrel to cool after 2-3 shots, the heat created may cause the bend to appear again. Whether it will go away after cooling is the question. I've never seen this happen but have heard from people I trust this does happen.

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The "old school" procedure for checking and correcting a barrel for bends or kinks is described in Clyde Baker "Modern Gunsmithing" - copyright 1933. Page 276 / 277. Bore is pointed at a window with a vertical wire or rod hanging in front - this casts a distinct shadow line down the bore - highlights any bends or kinks as barrel is rotated. A picture of it being done, with a barrel straightener in use at Remington Arms plant, is on page 151 of "The Modern Gunsmith" by Virgil Howe, Vol. 2 1944 re-print. Bores are not necessarily in the centre of the barrel so dialing in the outer surface is "assuming" that the bore is perfectly concentric. My brother bent a barrel on a 300 Win Mag when he rolled a snowmobile - Corlane's in Dawson Creek, B.C. straightened it back out very nicely - their comment: they like snowmobiles and quads - very good for their business...
 
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