I've seen mentioned a few times about bending/straightening a barrel to correct POI issues. What I haven't seen is a detailed way of doing the job. Anyone who's done this, how did you do it? Where should the bend be applied? Different process for a thin smoothbore barrel vs a swamped rifle barrel? Would like to understand the method for doing this.
Bending or straightening a barrel
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It's been explained in detail but buried in various threads with unrelated titles, maybe we can do it one more time and ask the staff if they will make it a sticky.
First off, usually "bending" means "un-bending", or fixing a curve or hook installed as a feature of the barrel being manufactured. It's really, really tough to drill a hole through a 4' pipe without it wandering a bit, and the thinner the barrel the more difficult it is.
First you need to figure out if it's straight or not and if not, is the bend causing your POI difference. This will tell you if resoldering a sight, drifting, or filing will correct your issue or if indeed the barrel needs to be tweaked.
Once you establish that the barrel is bend (need to read the light rings in the barrel, either from a light dropped down to the breech or by unbreeching the barrel and holding it up to a light colored, even wall or clear sky away from the sun. You can determine the center or apex of the bend and where exactly it is on the circumference of the barrel. Mark it.
Next, make a jig. This can be as simple as three wood blocks and a big C-clamp on a sturdy workbench. It is best to make saddles in the wood blocks, you can do that by drilling holes in a block and splitting it in half through the hole with a band saw or whatever. Soft "whitewood" is great for this.
Then you support the barrel between blocks CENTERED as far away from the apex of the bend as possible, bend up, and use your screw clamp and another block of wood placed at the apex to bend the barrel in the opposite direction. It will take a lot of deflection to produce permanent deformation, but once it starts to take a set, it goes quickly so be very careful. Bend the barrel and measure accurately how far it bent at the opposite apex, then release the pressure and see if it returned to exactly where it was before or is beginning to straighten. Check the light rings again if you think it moved. Repeat the bend, measuring, and checking until it starts to straighten out, then go just a little, tiny bit more (like another 1/16" past where it last deflected) and flex it by hand a few times to relax the metal. Recheck.
Put the gun together and go shoot it until it's hot and observe the POI on a target.
Repeat this process if necessary for fine-tuning. If the barrel channel is warped you may want to address that with a cramp frame, moisture, and some heat, but most fowling pieces and smoothbores have very thin forearms that won't affect the barre much even if warped.
Some notable gunbuilders will be along shortly to tell you how they do it in no time using the crotch of their favorite tree out in front of the shop. They have done a LOT more barrels than I have!
I'll attach a photo from my phone of me straightening a modern barrel here in a minute.
First off, usually "bending" means "un-bending", or fixing a curve or hook installed as a feature of the barrel being manufactured. It's really, really tough to drill a hole through a 4' pipe without it wandering a bit, and the thinner the barrel the more difficult it is.
First you need to figure out if it's straight or not and if not, is the bend causing your POI difference. This will tell you if resoldering a sight, drifting, or filing will correct your issue or if indeed the barrel needs to be tweaked.
Once you establish that the barrel is bend (need to read the light rings in the barrel, either from a light dropped down to the breech or by unbreeching the barrel and holding it up to a light colored, even wall or clear sky away from the sun. You can determine the center or apex of the bend and where exactly it is on the circumference of the barrel. Mark it.
Next, make a jig. This can be as simple as three wood blocks and a big C-clamp on a sturdy workbench. It is best to make saddles in the wood blocks, you can do that by drilling holes in a block and splitting it in half through the hole with a band saw or whatever. Soft "whitewood" is great for this.
Then you support the barrel between blocks CENTERED as far away from the apex of the bend as possible, bend up, and use your screw clamp and another block of wood placed at the apex to bend the barrel in the opposite direction. It will take a lot of deflection to produce permanent deformation, but once it starts to take a set, it goes quickly so be very careful. Bend the barrel and measure accurately how far it bent at the opposite apex, then release the pressure and see if it returned to exactly where it was before or is beginning to straighten. Check the light rings again if you think it moved. Repeat the bend, measuring, and checking until it starts to straighten out, then go just a little, tiny bit more (like another 1/16" past where it last deflected) and flex it by hand a few times to relax the metal. Recheck.
Put the gun together and go shoot it until it's hot and observe the POI on a target.
Repeat this process if necessary for fine-tuning. If the barrel channel is warped you may want to address that with a cramp frame, moisture, and some heat, but most fowling pieces and smoothbores have very thin forearms that won't affect the barre much even if warped.
Some notable gunbuilders will be along shortly to tell you how they do it in no time using the crotch of their favorite tree out in front of the shop. They have done a LOT more barrels than I have!
I'll attach a photo from my phone of me straightening a modern barrel here in a minute.
Last edited:
Here's me getting the 8" at 50 yards hook out of a 20-gauge barrel. The apex was 3" back from the muzzle. Had to make a tight-fitting mandrel to keep from collapsing the barrel.
I have only bent one straight, a straight octagon. Put it in the bench vise with protected jaws, and pushed gently in the desired direction, it does not take much to move it too much so sneak up on it is my recommendation.
Old timers like my mentor, would rap it over a solid wood object (log) at the point he thought would give the result intended, being a bit more cautious I chose the slow/controlled application of pressure
Old timers like my mentor, would rap it over a solid wood object (log) at the point he thought would give the result intended, being a bit more cautious I chose the slow/controlled application of pressure
Awesome write up. Thats's exactly what I was searching for. I did search the forum, saw lots of mentions of doing it but not the how to behind it. I like the idea of a sticky. Appreciate the detailed info, thanks.
I think @Flint62Smoothie has done one. I heard he hung it in some trees and did pull-ups on it. Shoots arrow straight now. 
Well … I’ve bent over a dozen by now …
Mind sharing the method you use? Is it the same as Ian mentions above? Thanks
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For those who have not had the experienced guidance of ‘old timers’ the blocks and clamps/vyce is the way to go.
The posts above are spot on.
As a Army armourer I was taught to bang them on a bit of solid timber standing on end, because we had to be able to straighten a barrel in the field, and we had lots of old barrels to practice upon.
The posts above are spot on.
As a Army armourer I was taught to bang them on a bit of solid timber standing on end, because we had to be able to straighten a barrel in the field, and we had lots of old barrels to practice upon.
Comfortably_Numb
The Evil Mike Brooks
I used to use the crotch of an apple tree. Stick the barrel in pull till you feel it bend the see what you have. I sold that place and lost access to that tree.
Now I put two 4x4s on the floor and place the barrel on top. I then step, stand and or bounce on the barrel until I feel it give.
It's really simple, even a caveman could do it.
Now I put two 4x4s on the floor and place the barrel on top. I then step, stand and or bounce on the barrel until I feel it give.
It's really simple, even a caveman could do it.
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HEY! I resemble that remark!
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I personally haven't straightened a barrel. My father ,being a machinist has. He put the barrel in a lathe and used a dial indicater to find the apex of the bend and used pressure till it was straight then looking down the barrel to see if any correction was needed. When straight he could see a perfect halo. He also straightened a barrel for me that I got free because you could see the bend and the fellow thought it was ruined.
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This caveman thanks you ...I wanna try this way ...
I suggest you put blocks under the part you're jumping on so when it does give permanently it doesn't fold in half. Bounce on it until you hit the blocks, if that's not far enough, put in a thinner block, repeat.
a friend of mine had a rifle with a Colerain barrel that shot so far to one side that the sights could not move enough to compensate. the company would do nothing to help. we took it out of the stock and "tweaked it" between a forked tree, it worked and shot Stright with the sights centered after the adjustment,,,,,,,,,,,,,
I'll take yer word for that. They ain't gonna mess with my barrels that way. And, yes, I have seen them banged against trees, posts, etc.
Comfortably_Numb
The Evil Mike Brooks
Then you'll just have to keep shooting around corners.
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I add a dial indicator to the bending. That way I can measure how much deflection it takes to before it actually bends. I can also track the progress of the bend. It is a simple math to determine how much bend is needed. I do my bending on a milling machine table with a lever.
I once got a m-12 12 ga barrel that was severely bent, pretend it is a fowler barrel. I made a mandrill to go in the bore to prevent collapse. I straightened that one using a large lathe to hold the barrel over the mandrill. It is easy to see and measure the run out that way. I did the bending with a lever. It came out very straight and still shoots POA today.
I once got a m-12 12 ga barrel that was severely bent, pretend it is a fowler barrel. I made a mandrill to go in the bore to prevent collapse. I straightened that one using a large lathe to hold the barrel over the mandrill. It is easy to see and measure the run out that way. I did the bending with a lever. It came out very straight and still shoots POA today.
It's amazing how much deflection a modern shotgun barrel will take before it quits springing back to the same shape.
