Checking for bent barrel

royce

royce

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Saskatchewan
Hi: The morning started ok until i went to pick up my rifle. I had grabbed it by the sling and the rivet let go. The rifle hit the cement floor on the muzzle end.:eek: It was like a pivoting action from the butt stock.It is a winchester model 70 XTR featherweight in 30-06 cal. The gun was not used after that incident. Is there any way I can check this barrel myself or should it be checked by a gunsmith?:confused:
Royce
 
courtesy of Guy M, gunsmith fom SLC;

Using diffraction rings to check barrel straightness.

First, when checking a barrel for straightness, you want the barrel
completely free of any outside influences, so, it is best to pull the
action from the stock to avoid any "false" reading. Next, pull the bolt
and clean and wipe the bore. (A) Remove the firing pin assy and
reinsert the bolt, or, (B) insert an unprimed cartridge case into the
chamber. While pointing the barrel at a light colored wall, look down
the muzzle and you will see the image of a target in the bore. See
attached photo. These are diffraction rings.

If the barrel is straight, or, otherwise without stress, the rings
should be perfectly concentric and uniform in thickness around it's
center. The image should form a perfect "target". See photo. If
however, the rings show any distortion what-so-ever, then you have a
barrel that is less than straight. The greater the ring distortion, the
greater the bend.

To see how little pressure it takes to distort the rings, try to bend
the barrel with your hands while looking at the diffraction rings. You
will see the rings begin to move and distort as you increase pressure.
If you had a way to suspend the barrel from the ceiling, at eye level,
you could watch the diffractions rings move about from the heat of a
candle. Diffraction rings tell a lot!

You might want to carry an unprimed case or two in the calibers you are
interested in when you go looking for a rifle so you can perform a
preliminary check before departing with your cash. If the diffraction
rings are a little out of whack with the barreled action in the stock,
it could indicate either a barrel straightness problem, or, some other
problem.

The diffraction rings have proven to be a valuable diagnostic tool when
troubleshooting other accuracy problems as well. But for now, and
because time is limited, this should help. Good luck!

straightbore.jpg
 
It's highly unlikely that the barrel will be bent from a drop. However, put a long spirit level or any straight edge on it all around the diameter. That'll tell you if it's been hurt. Isn't likely though.
It's far more likely that the crown has been damaged from hitting the concrete. If it's damaged you'll need to have that fixed. Look for any dings on the muzzle. You can do it yourself or take it to a smithy. Brownell's sells a re-crowning tool or carefully use a rotary tool(Dremel is a brand name). Do not use a file. It's really easy to screw up the muzzle with a file.
 
Take it to a gunsmith and have it re crowned so it looks good again and will shoot as good as it did before....

You did not bend the barrel.
 
rgv said:
courtesy of Guy M, gunsmith fom SLC;

Using diffraction rings to check barrel straightness.

First, when checking a barrel for straightness, you want the barrel
completely free of any outside influences, so, it is best to pull the
action from the stock to avoid any "false" reading. Next, pull the bolt
and clean and wipe the bore. (A) Remove the firing pin assy and
reinsert the bolt, or, (B) insert an unprimed cartridge case into the
chamber. While pointing the barrel at a light colored wall, look down
the muzzle and you will see the image of a target in the bore. See
attached photo. These are diffraction rings.

If the barrel is straight, or, otherwise without stress, the rings
should be perfectly concentric and uniform in thickness around it's
center. The image should form a perfect "target". See photo. If
however, the rings show any distortion what-so-ever, then you have a
barrel that is less than straight. The greater the ring distortion, the
greater the bend.

To see how little pressure it takes to distort the rings, try to bend
the barrel with your hands while looking at the diffraction rings. You
will see the rings begin to move and distort as you increase pressure.
If you had a way to suspend the barrel from the ceiling, at eye level,
you could watch the diffractions rings move about from the heat of a
candle. Diffraction rings tell a lot!

You might want to carry an unprimed case or two in the calibers you are
interested in when you go looking for a rifle so you can perform a
preliminary check before departing with your cash. If the diffraction
rings are a little out of whack with the barreled action in the stock,
it could indicate either a barrel straightness problem, or, some other
problem.

The diffraction rings have proven to be a valuable diagnostic tool when
troubleshooting other accuracy problems as well. But for now, and
because time is limited, this should help. Good luck!

straightbore.jpg
Click to expand...

this i beleive tells u only that half of the barrel is straight
or not . u need to do the same for the oposite end of the barrel. IIRC
 
jbunny said:
thats not the way i was taught. when u look through the
apature , u are checking the far end of the barrel.
u have to move the apature to the other end of the barrel
to check the other half.
cheers
Click to expand...

Look through a straight barrel while holding it in a vice... then push it to the side slightly - the rings will become non concentric... it does not matter which end you are looking through.. at least that had been my experience. A bent barrel is a bent barrel.
 
guntech said:
Look through a straight barrel while holding it in a vice... then push it to the side slightly - the rings will become non concentric... it does not matter which end you are looking through.. at least that had been my experience. A bent barrel is a bent barrel.
Click to expand...
page 150 , the modern gunsmith, by James How. when this part is straightened, reverse the barrel in the fixture and work the oposite end. does any body know ron smith,
bevan king. they could tell you
 
jbunny said:
page 150 , the modern gunsmith, by James How. when this part is straightened, reverse the barrel in the fixture and work the oposite end. does any body know ron smith,
bevan king. they could tell you
Click to expand...

We weren't discussing how to straighten a barrel. That is different than looking at the "rings" shown in that picture.

We were discussing what light reflections look like in a bent barrel... those "rings" shown in the picture look the same from either end when a barrel is bent.

Take a barrel and try it.
 
Well I checked the barrel and every thing seems fine. Took it to the range and put some rounds through it. The bullets hit were the gun was pointed. So thanks for all the info in regards to this matter. Royce
 
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