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Old October 20, 2018, 11:20 AM   #1
tangolima
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Straightening rifle barrel

Got a kinda rare c&r milsurp rifle with barrel slightly bent downward about 10" from the muzzle, so it is shooting way low and to the left. Anywhere I can send it to have it straightened? Thanks.

-TL

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Old October 20, 2018, 11:50 AM   #2
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Are you sure the barrel is bent? What you described is typical of a shooters flinch.
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Old October 20, 2018, 12:36 PM   #3
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Barrels get bent. It happens.
I have a Marlin .30-30 barrel that's bent down and slightly to one side, about 7" from the muzzle. The deflection isn't substantial - only about 0.030" off of bore axis - but it's there.
Shoots fine, once sighted in. But it is, definitively, bent.


Tangolima, I have no suggestions for you. But barrel straightening is usually approached in one of two ways by 'smiths:
1. Just clamp it in a vise, or wedge it between two solid objects, and yank on it until it looks good.
2. Very precise, small adjustments, done with V-blocks or round stock, in a hydraulic press.
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Old October 20, 2018, 01:16 PM   #4
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"...Barrels get bent. It happens..." Yep. With milsurps it's usually by guys playing bayonet fighter. Unless that one is of serious value (in which case some would cry about shooting it at all.) it'd probably cost more than it's worth to try straightening the barrel.
Before you do anything put a straight edge like a 1 to 4 foot spirit level on it to be sure. A 12" level runs $13.29 in Home Depot. Tool rental shops will have 'em too.
"...way low and to the left..." If the barrel is bent, that suggests there's a bedding issue too. Or possibly(and better) just a bedding issue.
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Old October 20, 2018, 02:53 PM   #5
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It is an arisaka type I made by carcano for the Japanese imperial navy. A bit on the rare side but not at all valuable. It was in sorry shape when I got it. The bent barrel was noticed when I peeked down the bore, it is down and to the left.

It shoots pretty well. Tight group 8" low and 4" to the left at 25yd with battle sight. I read about the barrel straightener and how it was done at gun factories. I thought about doing it as suggested by Franken. But I wouldn't mind letting a professional do it for a fee if he is available. For now I probably will just drift the front sight to the left and crank the ladder sight way up and keep shooting. When I finally get in the mood, I will give an arbor press a try. If it doesn't work out I will find a replacement barrel.

Thanks gentlemen.

-TL

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Old October 20, 2018, 03:46 PM   #6
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tangolima:

The factories did (and some still do) that, but a gun smith is not setup with the optical system and fixture to do so.

Keep in mind, its not just the exterior, its how the hole was bored in the blank originally.

I don't know anyone that is.
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Old October 20, 2018, 03:47 PM   #7
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Quote:
Are you sure the barrel is bent? What you described is typical of a shooters flinch.
The OP clearly describes it is bent, where and how much. What does it contribute to question that?
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Old October 20, 2018, 04:33 PM   #8
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Quote:
Originally Posted by RC20 View Post
The OP clearly describes it is bent, where and how much. What does it contribute to question that?
In his original post he did not tell us how he knew it was bent. It's well known that a flinch often results in low and left shot placement.

Last edited by JohnKSa; October 23, 2018 at 01:36 PM. Reason: Eliminated excessive snark.
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Old October 20, 2018, 06:32 PM   #9
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One day I had a lot of 30 cal. barrels to check so I made a made a bent barrel checker, I even took the time to explain how the tool is made. The best response I had that year was; "that might work".

I make the 308/30 cal. checker from an 8mm bent barrel checker.

I can not imagine how out of shape you guys would get if I told you it would take me a month to dig out the barrel straightener.

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Old October 20, 2018, 09:47 PM   #10
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Barrels are easily straightened using radius ( or v ) blocks, a dial indicator, and hydraulic press. If the bore is concentric with the exterior then the barrel will be straight after no more deflection is indicated. One of my early Winchester model 69 rifles had a total indicated runout of around 1 3/4 inches when given to me, and shoots bug hole groups with the right ammunition now.

At the time I made a living by straightening bent motorcycles and had access to a large assortment of radius blocks used for straightening fork tubes. It was quick work even for me, I wasn’t the fork tube genius that my coworker was, I specialized on mag wheels and frames which are straightened NOTHING like tubes.....but it was really simple.


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Old October 20, 2018, 11:22 PM   #11
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Hmm... The bore is supposed to be coaxial with the barrel's exterior, but it may not. The bore's straightness is traditionally checked by peering down the bore. Old gunsmith books describe how it was done. The straightener has huge hand wheel over the smith's head, so that he can do the straightening while peering down the bore.

-TL


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Old October 21, 2018, 12:59 AM   #12
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Quote:
Hmm... The bore is supposed to be coaxial with the barrel's exterior, but it may not (...)
I have a Shilen "Match" barrel that was chambered for a wildcat (consider it .243 Win "ultra-match"), which turned out to have a 0.093" deviation.
Deviation?
Yea... The bore in the barrel deviates from the bore axis by 0.093" at the muzzle. It is NOT concentric with the exterior.
It shoots like a champ, though...


Quote:
I can not imagine how out of shape you guys would get if I told you it would take me a month to dig out the barrel straightener.
Start digging.
We'll be here.
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Old October 21, 2018, 07:06 AM   #13
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Mr. Guffey,
I am in total agreence with Frankenmauser, as i am curious as to what a barrel checker would look like.

I remember seeing literature from Savage showing their person checking bore straightness. He would appearently look down the bore, and had what looked like an English Wheel to straighten them.
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Old October 21, 2018, 11:30 AM   #14
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"...made by Carcano..." Everything you ever wanted to know about 'em is here. It's basically a Type 38 made in Italy. One of 'em sold on gunauction.com for $575 back in 2011.
http://www.nambuworld.com/typeipix.htm
Using an arbor might crush the barrel rather than straighten. It'd be a trial and error thing too. The thing's condition would determine how much it'd be worth doing.
"...how the hole was bored..." Drilled not bored.
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Old October 21, 2018, 01:05 PM   #15
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https://images.search.yahoo.com/imag...olphin_int_abt

Here is how it was done at Springfield Armory
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Old October 21, 2018, 02:41 PM   #16
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It should be clear from the various posts, that the goal shouldn't really be to straighten the barrel, it's to straighten the bore.

However, that could prove difficult and straightening the barrel would probably help even if it's not the ideal solution.
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Old October 21, 2018, 03:02 PM   #17
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Quote:
Originally Posted by T. O'Heir View Post
It's basically a Type 38 made in Italy. One of 'em sold on gunauction.com for $575 back in 2011.
http://www.nambuworld.com/typeipix.htm
Read more and you will know it is not really a T38. I paid way less than $500 for mine. But I had to repair a few things, including this crooked barrel.

Quote:
Originally Posted by T. O'Heir View Post
Using an arbor might crush the barrel rather than straighten. It'd be a trial and error thing too.
With proper supports, I am certain the barrel will bend before crush.

Quote:
Originally Posted by T. O'Heir View Post
Drilled not bored.
It may be bent in this case.

-TL

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Old October 21, 2018, 05:40 PM   #18
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Quote:
Originally Posted by RC20
The factories did (and some still do) that, but a gun smith is not setup with the optical system and fixture to do so.
On my tour of the Savage factory ten years ago, I watched them straightening barrels. The setup was two V-locks and what amounted to an arbor press arm with a lot of mechanical advantage but with another v with a protective coating bearing down on it. The optical system consisted of angling the apparatus up far enough to see the factory window muntins. The bend was determined just by sighting on the muntins through the bore and looking for their reflections to be asymmetrical. Worked just fine. A printed grid that is brightly illuminated would do the same thing.

Whether you want to straighten the bore or the contour may depend on your purposes. For historical purposes, it may be the contour as it is less likely mass wartime production included straightening bores carefully. But I know some German Mauser barrels were straightened, so you'd want to check the manufacturing history to decide that.

Barrel steel is not so hard that it is difficult to bend. V-block padded with plastic should do fine for both supporting the ends of the barrel and for pressing down on it with the press of your choice.


Quote:
Originally Posted by linestretcher
It's well known that a flinch often results in low and left shot placement.
That's true for a right-handed pistol shooter, but a right-handed rifle flinch is often low and right. Vice-versa for left-handed shooters.
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Old October 22, 2018, 12:08 PM   #19
4V50 Gary
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We whacked the barrel against a workbench to straighten it. That's the primitive way when you don't have the fancy straightener.

Found these images on the net and this is what you should use. The top jaws are stable and the bottom jaw moves up and down via the overhead ship's wheel. You place the barrel's dark spot on the bottom jaw and then rotate the wheel to press the barrel up against the top two jaws. By looking down the bore and looking at the shadow, you'll see whether that dark spot indicating a bend is gone. It should be a nice "V" shadow. Without further adieu, I present these images:



Here is it being used:



Poor man method it can be done in an arbor press. In this case, it's best to have two people, one on the vise and one whose eyeball looks down the barrel.

You don't need an optical system either. You can see down the barrel and look at the shadow casted to see if it's straight.
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Old October 22, 2018, 12:13 PM   #20
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I'd contact Springfield Armory to see if they'd let you use theirs. Dress up in a period costume and make a historical presentation of it. Of course, the public has to be invited.
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Old October 22, 2018, 02:21 PM   #21
tangolima
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That's exactly what the book said. I saw such a straightener at the Springfield armory museum.

I may try the poor man's method when I run out of things to do. The book describes how to detect which way the barrel bends, but it doesn't tell how to determine the exact location of the "elbow". Guess it would a matter of experience and trial and error. That may be why the operator needs to keep looking down the barrel while working the wheel.

-TL

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Old October 23, 2018, 01:21 PM   #22
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Also notice the angle? There is a bright light out there.

I believe some used some kind of light system that reflected how bent it was.
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Old October 23, 2018, 04:45 PM   #23
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They do. It's called daylight. You look at a window up high enough on the factory wall that traffic crossing the factory floor doesn't interfere with your view.
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