How to bend a smoothbore barrel?

M

maillemaker

New member
I have an Armisport 1842 that shoots about 4"-6" to the left at 25 yards. To hit the bullseye, I have to shoot "in space" to the right of the bull.

I would like to investigate bending the barrel to bring the point of aim into compliance.

I have thought about grinding off the front sight cast into the front barrel band and replacing it with a brazed-in brass one, but the current sight is already offset to the left and to move the point of aim it would need to be moved even farther to the left.

Also the stock has already been glass bedded. Will this prevent me from being able to bend the barrel?

Steve
 
Makes me wonder if the barrel is straight. Can't tell that until the breechplug is pulled out.

I straightened a barrel once. Whacked it on a table. Old gunsmiths swung it against a tree. Now, the factories had a special jig you put the barrel in and the you peered down the bore to check. There was a large wheel you could spin to put pressure on the barrel to straighten it.

I saw one at the Ruger factory once.
 
I have read some articles that say you can take some 4x4 and cut off some sections, then drill a barrel-sized hole in them, and then saw them in half, making cradles.

You support the barrel at either end with two cradles, and then apply pressure with another cradle in the middle in the direction you want the POI to move.

I'm wondering if the glass-bedded stock will eliminate the ability to bend the barrel though. I understand only a few thousandths of an inch are required - maybe the stock would give?

Steve
 
You will have to make room in the old bedding for the barrel to fit. Depending on what it was bedded with that might be a chore. You could just find a new point to aim from on the breech.
 
Can do but is it really the problem

The model 1842 Springfield has no rear sight.
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I am indicating that it does or should have a rear sight. So what am I missing?

I have read some articles that say you can take some 4x4 and cut off some sections, then drill a barrel-sized hole in them, and then saw them in half, making cradles. You support the barrel at either end with two cradles, and then apply pressure with another cradle in the middle in the direction you want the POI to move.
Click to expand...

A number of years ago, I made such a tool like this and still use it for other applications. Even though it is a bit crude, it works. On a barrel, I make absolutely sure that the barrel is truly bent and use a laser to help me confirm the bend and where it might be. Not very scientific but it helps. One you locate the area that needs bending, you mark it and press past the area as the barrel will want to bounce back to it's original position. The process is a little tricky but can do. ..... :)
 
Awhile ago I saw a video of the Pedersoi factory, there is a step in the barrel process where they are straightening barrels after one of the machining steps.
 
Pahoo - you use a laser? You are sophisticated.

I used a vertical line and held the barrel up against it. Look down the barrel and center it with the vertical line. The "v" image in the barrel should be equidistance down the barrel.

I think Walter J. Howe's book, Gunsmithing, discusses barrel straightening. If not Howe, then perhaps Ned Roberts' Muzzle Loading Cap Lock Rifle.
 
I am indicating that it does or should have a rear sight. So what am I missing?
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The M1842 Springfield does not have, nor is it supposed to have, a rear sight.

Being a smoothbore, it was not considered accurate enough to benefit from having one. All it has is a blade on the front barrel band.

I used a vertical line and held the barrel up against it. Look down the barrel and center it with the vertical line. The "v" image in the barrel should be equidistance down the barrel.
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Gary: Can you explain this a bit more? Thanks!

Steve
 
Hardly

You are sophisticated.
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Hardly, just a bit lazy, perhaps. the laser casts a straight line and just walk it around the outside of the bore and cast the line from muzzle to breech. On some occasions, it even reveals some barrel rings. Not always all that useful on swamped barrels. When the cast beam encounters a variation or curve, it stops or brightens up. Your vertical line/plain sounds interesting. ..... :)

Be Safe !!!
 
Smoothbore

Four to six inches left at 25 yards. The gun is a smoothbore. It is similar in many ways to my fowler.
Forgive these questions but... for clarity...how much have you used this gun? What size ball are you loading? What thickness patch? What is the powder charge? How consistent is elevation?
Before you go to the trouble of bending the barrel, perhaps there are other courses of action. Experimenting with the ball/patch/charge is one. One other course is to file one side of the muzzle. This does not take much filing and is correctable if you are careful.

From the "Traditional Muzzleloading" website:
"I know bending smoothbore barrels has been a common practice for adjusting POI (point of impact) ever since people first started shooting smoothies,... but I ran across some information that I wasn't aware of, that was also used to change a smoothbore's POI to a lesser degree.

quote:..... "First, I am all in favor of bending barrels to correct larger errors in POINT OF IMPACT(POI).

Filing the muzzle is to make the changes:
a. If you can't bend the barrel for some reason( as in DBL shotguns- where you are concerned with breaking the solder between the barrels, or where one barrel is more off- or off in a different direction than the other); and
b. For small deviations for the POI from the POA (point of aim).

For my purpose, I am treating this subject as if we are using a DB shotgun, so that the bead is held at the 12 o'clock( clock dial) position to the target.

Now, lets assume the LEFT barrel( Your left as you look down the barrels from the butt stock) is shooting LEFT- to 9 o'clock, and the center of the pattern is 12+ inches off from the POA.

You want to move that shot so that it more closely impacts the center of the pattern at the POA.

WHAT TO DO:

FILE THE LEFT BARREL MUZZLE AT 9 o'CLOCK. It sounds counter intuitive, until you think about what is going to push that shot one way or another. Its the Gases pushing the shot, and wads or cards behind the gas out of the muzzle that will move the shot in one direction or another. By filing the muzzle at 9 O'clock, GAS will Escape out the muzzle at 9 o'clock FIRST, and push the wad and shot towards 3 o'clock, moving it in that direction to get closer to the POA. The more you file the muzzle, the more the load of shot will move in the OPPOSITE direction."

Of course, the Springfield has only one barrel. The procedure is the same.
Note: I have not done this. I have read about it on a number of websites.
What I did to my fowler when I wanted to shoot round balls was to fashion a rear sight from some brass stock. I was careful about fitting the base of the sight to the barrel. I attached it with Loctite 380....marvelous stuff....and it has stayed put. Then I filed the sight so that the balls were on at 50 yards.
 
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Four to six inches left at 25 yards. The gun is a smoothbore. It is similar in many ways to my fowler.
Forgive these questions but... for clarity...how much have you used this gun? What size ball are you loading? What thickness patch? What is the powder charge? How consistent is elevation?
Before you go to the trouble of bending the barrel, perhaps there are other courses of action. Experimenting with the ball/patch/charge is one. One other course is to file one side of the muzzle. This does not take much filing and is correctable if you are careful.
Click to expand...

I have been shooting this gun in N-SSA competition for about a year now. Bought it from a retiring team member last Christmas. He had already glass bedded it.

It is an Armisport 1842 that is stock except for having been glass bedded.

N-SSA competition does not allow patches around balls for smoothbores, though you can wrap the balls in aluminum foil if desired. I do not do this, instead I use the method proscribed by our team's top smoothbore shooter. I cast an RCBS .678 round ball using wheel weight lead. I then remove the sprue with a Mike Rouche sprue cutter. I then roll the ball between two files to roughen up the surface. I then dip the ball in Alox (Xlox) twice. I use 70 grains 3F Goex as this produced the best group.

From a bench it will blow a single ragged hole in the paper at 25 yards.

At my first N-SSA Nationals last week, I managed to achieve rank #10 out of 66 shooters in 50 yard smoothbore, in the top (Expert) class.

The gun shoots good groups, just not to point of aim. I'd like to modify it to shoot point of aim.

The muzzle filing sounds interesting also.

What I did to my fowler when I wanted to shoot round balls was to fashion a rear sight from some brass stock. I was careful about fitting the base of the sight to the barrel. I attached it with Loctite 380....marvelous stuff....and it has stayed put. Then I filed the sight so that the balls were on at 50 yards.
Click to expand...

Adding a rear sight to the M1842 is not permitted per N-SSA rules.

Steve
 
I think I might be tempted to relieve the bedding compound on one side and see if it would make a difference.
Maybe not relevant, but I once came upon an 1890 Winchester .22 that shot so far off at 30 yds. that I had the front sight drifted probably 1/4 inch off the left side of the barrel before I could center up POI on the target. It had a replacement Numrich barrel on it so I figured what the heck! There was a large picnic table near me and I placed the barrel between two of the boards on the top of it and gave it a nudge with my knee. After a few more nudges back and forth I had the front sight centered again and it shot where it should.
I doubt you would want to do something like that with a nice rifle such as you have.....just thought I'd pass it along.
 
I once saw a fellow down at Friendship - over on the primitive range - who was having problems with his smoothbore trade gun. I won't mention who it was but he was well known (at least years ago) for being a little on the "eccentric" side. :eek::roll eyes:

Anyways - his was not shooting where he wanted it to so he dismounted the barrel, walked over to a tree that had several trunks gong up - put it in the crotch of the tree and gave it a gentle pull on the breech end to "straighten" it out. All of us were looking on and most of us had a kind of a smirk on our face - but believe it or not - it worked.

Not that I'd recommend that "fix" for yours though. :) I'm sure that it was probably done just that way though by many or our ancestors who needed to straighten their barrels. Not much different than placing in a vise and giving a mental tug.
 
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