barrel bending

mooncoon

mooncoon

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I have been frustrated with my trade gun for some time because it shot about 4" below the aim point at 25 yards and using the bottom of the front sight. I had bent the barrel slightly in the past but obviously not enough. Finally found a round two-it in the shop and bent the barrel some more. It now shoots to the point of aim or slightly higher at 25 yards using the top of the front sight.

Interesting point is just how much I had to flex the barrel to change the point of impact. When the C clamp was removed. the barrel appeared to retain about perhaps 40 thou of bend between the two wooden cradles supporting the barrel.

cheers mooncoon

barrelbendingb.jpg
 
i had a old Single Shot 303 That i had to do this too. Was 1Ft off at 25 Yards! (to the left) Well We Stuck it in a Hole On a Atv Trail And Drove over it! Well After that it was maybe 3" off to the Right! So Thats the Way we used it LOL! (this was 10+ YEARS AGO! ) i used it to get a deer at 100 yards that year!

Then i sold it on the EE Last year! with a 12G Barrel
 
Good photo, Mooncoon. Nice to see somebody keeping the old ways alive.

Guys, I hate to mention this, but this is standard practice for regulating double guns and double rifles, has been for centuries. Check your old doubles very carefully; you just might get a surprise.
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I didn't have any easy way to measure how much the barrel was bent before and after the process, so I made a long wooden wedge, slid it under the barrel with no clamp but on the cradles, and marked where the barrel crossed the wood. Bent the barrel then checked again. The wedge would not go as far under the barrel, indicating that there was a permanent bend down. You can measure the thickness of the wedge at the first and second location to get an approximate guesstimate of how much bend there is

cheers mooncoon
 
Barrel straightening was a standard part of the production process and you can find a lot of pictures of the presses used, online.
Brownell's used to sell (maybe still do) a long bar with a set of padde loop clamps and a screw jack built in, for bending shotgun barrels.

What is old, is new again, eh?

Cheers
Trev
 
:needPics:
billybob said:
I am afraid I am not so technical. While at the range,
I put the barrel on two lead pillow blocks and jump on it .
then reassemble and test fire, repeat as necessary. I once had a 45 70 rifle shooting 2 feet right at 100 yards, after 3 jumps X ring from then on!

Mind you some people think I am nutz, but ?

Cheers Rob
Click to expand...

I'm afraid we require pictures of this technique, it sounds pure awesome! Truly an art, not a science, as the barrel strength and jumper weight must be taken into account, not to mention jump position...
 
I tried standing with one foot on the barrel and while it bent, apparently not enough because it did not change the point of impact. What I liked about the clamp was that it gave me a bit of control over how far I was bending the barrel each time. More or less go down to how far I went the time before and increase by 1/2 turn then check to see if it accomplished anything

cheers mooncoon
 
I played with a barrel bending press at the Numrich Arms shop back in the mid 90's. Basically a large wheel operated screw jack with two clamps, one at each end. Also had a jig for sighting through the barrel to check the "straightness" as they said. It was a pretty interesting set up. - dan
 
I have seen videos of barrel straightening at barrel making factories and they used a large screw jack coming down from the ceiling and operated by hand more or less like the one that you used. In the videos I have seen, the jack ended in a sort of U shaped piece with the two ends about 8- 12" apart and which forced the barrel onto a single piece in the center.
I have tried looking down a barrel at a piece of string and still can't see the shadow indicating where the bend is. Must take a lot of experience from what I can see

cheers mooncoon
 
Before trap guns were commonly available with adjustable ribs and stocks there were some gunsmiths that would bend shotgun barrels to raise the point of impact. As it was described to me (more than 20 years ago) a good gunsmith who knew how could gently smack a shotgun barrel rib-and-all over a bag of lead shot to put a very slight upward curve to the barrel. This would allow the trapshooter to hold the bead below the target and still break it. Now days you just adjust the rib and/or stock.
 
I have a sweet kentucky style 45 cal that might be in for some clamp pressure now after reading this thread. It has very low sights that are non adjustable, other than by FILE AND HAMMER,and it likes to shoot very low .
I bet if I pull a tight thread along the barrel it will show it is bent down now.
Pete
 
petew said:
I have a sweet kentucky style 45 cal that might be in for some clamp pressure now after reading this thread. It has very low sights that are non adjustable, other than by FILE AND HAMMER,and it likes to shoot very low .
I bet if I pull a tight thread along the barrel it will show it is bent down now.
Pete
Click to expand...

I think you would be far better advised to install a taller rear sight

cheers mooncoon
 
Great idea with the c clamp, I've straightened pump shafts using a similiar method with a press and dial indicator, very controlled also., but always enjoyed watching machinists using a oxy-act torch straightening shafts in the lathe, they would use a series of "heat spots" along the side to make it shrink on that side. Always more than one way to skin a cat :)
Thanks mooncoon for sharing.
Cheers nessy.
 
Thermal straightening is great, I have done lots of it for Pump Strains, but for a gun I would be afraid of doing some damage to the barrel , at the least it would be changing grain structure, and it would definately warrant a new Proof test , it would require a new blue / brown job too.

I agree a taller sight is the logical and practical choice if the barrel is straight.

Pete
 
as long as you don't cool it quickly, loss of strength should not be a problem. Muzzle loading barrels are sometimes made of low carbon free machining steel and others are made of 4140 which is affected by rapid cooling

cheers mooncoon
 
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