bending barrel

didn't want to hijack the smoothy shooting low thread so i'll ask here Iv'e also got a smoothbore that shoots 5 to 6 inches low at 25 yards if I were to bend the barrel up to get it to shoot point of aim how would I go about that I would think a gradual bend in the full length of the barrel would be best but how do you do it? it has no rear sight and a low front sight that cant be lowered enough to shoot point of aim. thanks Duane

A pair of 4x4 blocks, and a large C clamp. Set on the edge of a heavy duty work bench or other strong support. I make a contoured block for the barrel, maybe 2/3" long for the clamp to bear on. If you remove the breech plug and look down the bore, you will see ring shadows of light. If the barrel is bent, these shadow rings will be egg shaped. If straight they will be round. This will also give you an idea of where to pressure the barrel, and to know when to stop. With everything in place, measure or make a heigth gauge of sorts to measure your progress. Barrels are much more springy than you might imagine, and have to be forced beyond straight for them to take a set. Sometimes well beyond. Another method used by some is to simply bend in a tree fork, or other similar arrangement, but I prefer more control of what I'm doing.

Wick: The "bend the barrel" idea has always intrigued me. Once the barrel is set up in the jig, is it then a process of trial and error? I bend it a bit, see that it has taken a bit of a set and then put the gun back together and shoot it. Then - since I probably won't get it right on the first bend - I have to take it apart, etc., etc. Is that correct or am I over complicating the process?
How much does the bend interfere with the fit of the barrel to the stock? I'm thinking about those little brass pins that hold the two together; there doesn't seem to be a lot of wiggle room there.
Pete

This subject has been discussed several times in the past. Do a search for barrel bending and you will see some very clever set ups for bending and controlling how much bend to put in your barrel.

I use two blocks of known dimensions. Then I use drill bits under the center of the barrel to guage how much bend I'm getting.
Example: Using two 3/4 inch blocks at each end of the barrel I can put a 1/2" bit in the center and bend until the barrel touches the bit. Then replace the 1/2 bit with whatever size bit will still fit under the barrel to see how much I've gained. Bending only 1/4" probably won't gain anything, it will spring back so then go with a 1/4" bit, bend till it touches then measure again. Once you see a 1/8" gain assemble your gun and shoot it to see where it's hitting. Caution :: you can go too far! I shouldn't have to explain how I know that.

This is only one method and it works for me. I have to be ultra careful because I'm usually/always doing it on someone else' gun so can't afford to screw it up. :rotf:

L. Dog

Most smoothbores come with half stocks. You normally do not have trouble with the location of hangers or pins. However, if you are working with a replica Brown Bess, or a Charlesville, or Fusil de Chase, or Some Fowlers, you do have a full length stock.

Normally, bending the barrel does not involve enough "bending" that you are going to have much trouble with pin alignment in the stock. The forward pin might have to be relocated.

As to how to measure your progress, Wick has already given you two ways- looking at the " rings " of light in the barrel as you progress, to see how out-of-round-- or oval-- they get, and by measuring the amount of bend at the middle of the barrel with ordinary measures, while the barrel is in the clamps. Because of "spring back", you then also have to re-measure the amount of bend AFTER you remove the clamp, to see what, if any, effect you have had at all.

Before bending a barrel to correct a POI error, check several different "Causes" for a Low POI:

a. What is the bore diameter? Compare that to the Ball and patch you are using.

I found out that my 20 gauge fowler was closer to a 19 gauge fowler, and when I obtained the proper sized WADS, the POI rose 8 inches at 25 yds!

b. Check the muzzle to make sure that the muzzle is SQUARE to the bore!

I have owned a couple of shotguns where squaring the muzzle to the bore changed the POI radically, and "cured" the problem.

c. Check the powder charge being used. Sometimes you simply need to use MORE POWDER than you thought you needed, or switch from 2Fg to 3Fg powder.

d. If your gun does NOT have a rear sight, your EYE is the rear sight, as with any shotgun. Raising the Comb of the stock will raise the POI of the gun, just as raising the rear sight on any rifle will raise the POI.

It is much easier to raise the comb of any stock( glue on moleskin, or pieces of leather) until you get the height you need. You can have a stock maker with a pattern lathe make a new stock with those dimensions for you, if you want a stock without the added on layers of material on the comb.

Particularly with round or half round/half octagon barrels, I find that the POI can be off several inches depending on the ball and patch combination used- as the barrel vibrates differently pushing a solid RB down it, compared to how it handles shot loads of the same weight.

This has everything to do with "Barrel Harmonics", and you simply have to deal with each barrel as a separate entity- with its own likes and dislikes--- as you work up loads.

If you have access to a CHRONOGRAPH, use it to determine ACTUAL Muzzle Velocity of a PRB load in a smoothbore- don't Guess! :nono: I found out that my wads were too small for the barrel in my fowler because the chronograph immediately( first shot) told me that my MV was at least 200 fps slower than what I should have expected. It was then I checked the ACTUAL Bore diameter of the barrel, and found it was way oversized for 20 gauge balls and wads. When I used 19 gauge wads, the MV came up to expected velocities, and the POI also rose.

Only after eliminating these "causes" should you go to bending the barrel. Yes, some barrels need to be bent. A full-octagon barrel will be the most difficult to bend, but it can be done.

You should be able to work out the math to determine how much the muzzle must be "bent" upward to change that POI at any given range. Convert the distance from the muzzle to the target into INCHES, and then measure the barrel inches. The drop or low POI can also be fixed in inches, and the three numbers can be used to determine how many fractions of an inch, or Thousandths of an inch, the muzzle must be raised to bring the POI up to POA.

Best wishes. Keep us posted on what you learn about that barrel. :hmm: :thumbsup: :thumbsup:

Remember the shadow rings. Bend until they are round, rather than oval, then test fire for effect. You will be close, if not right on, and often be able to make further adjustments with the sight.

Wick (et al). Thanks for the responses.
Search was no help. There is plenty of info about how to bend a barrel. I understand and can do that part. The part of the process that I was concerned about was "how much" does one bend the barrel in order to achieve a given amount of change in POI.
From what I can see, this can be a pretty labor intense process involving taking the barrel off the stock, bending it, measuring the bend, reinstalling the barrel, test firing the barrel, and then - maybe - having to do the whole procedure over again if the result is not satisfactory.
Understand, please, this is not a criticism of then idea or the method, I was requesting info that an experienced barrel bender might be taking for granted. Y'know - how does one determine when enough is enough concerning the bend? It seems as if trial and error is the answer....and that's OK.
Just wanted to know.
Also - Wick -

you will see ring shadows of light. If the barrel is bent, these shadow rings will be egg shaped. If straight they will be round.

Click to expand...

Remember the shadow rings. Bend until they are round, rather than oval,

Click to expand...

Which? Not meant to be a silly question. I've never done this and want to get it right.
Pete

I am not that scientific about it. I bend it a bit and shoot it. If that isn't enough, or is too much I do it again. :haha:

Am I correct in thinking that the fore stock will bend to the new shape of the barrel on reassembly?

Brits.

yep.. there isn't much wood there so it will go with the barrel. Now wood and steel shrink and expand as everyone knows, and the barrel lugs should be slotted to allow for the wood movement.

If you have a single barreled modern break open shotgun, open it and look through the bore at a lighted background. You will see reflected rings of shadow light all through it. These rings will be round unless you have a bend. If the barrel is bent, these will be ovaled at the bend area. If your gun is shooting as low as you say, it is probably bent, and you will see these rings as ovals. Straighten until you see them as round as can be, then test fire. Nothing wrong with Roys method either.

Thanks. That helps. I was operating under the assumption that the barrel is straight. Mebbe it ain't.....but I wouldn't have had that thought.
Pete

I have never done it but have seen it done. The bend it between 2 trees . Thought I was going to throw up. lol

I cringe every time I hear about bending a barrel; sorta like hearing about the "low kick".

I just (as in today) finished a barrel bending on a trade gun. Initially, the gun shot low by 6 to 8 inches at 25 yards. Bent it yesterday with the 2 inch block and C clamp method that was described above.

I initially held the barrel 2 inches above the bench surface, and bent the barrel to the bench surface. When reassembled, the gun shot 8 to 12 inches high. Last night, I turned the barrel over 180 degrees, and bent it back to neutral, and then continued so that the deflection was 1 inch from the bench surface (1/2 of the way to the bench). Reassembled the gun, and shot it again this morning. The gun shot 2 inches low at 25 yards. I took it home and re-bent the barrel so that the deflection was 1 inch at mid point again. I took it back to the range. It shot dead on at 25 yards, and if I hold the barrel on the bull, was on at the 50 yard distance. Windage was always dead on.

I've tried the sighting methods and the different powder charges and patch thicknesses that have been described, but they haven't worked as well and as reliably as the bending method.

I also tried to measure deflection with calipers, but it didn't help much.

You do have to remove the barrel from the stock, but since I made the stock from a block of walnut, that is no great effort: 3 screws, and 3 pins.

I too gulped and hesitated when I read here about barrel bending, but it was surprisingly easy and effective.

The hardest part for me is to know when to quit.

Well that convinces me :thumbsup:

Well done.

Brits.