Barrel regulation of SXS

[Wayne/Al]

I have a PEDERSOLI 12 ga SXS . When I shoot the left Barrel the pattern is about 3/4 to the left of the point of aim. When I shoot the right barrel I get the same results to the right. Not really a problem , over the years I have learned to adjust as necessary. Just as a matter of what you should expect as far as barrel regulation of a SXS what have other members experienced with their double barrels. BTW I was shooting from 25 yards.

 

[denster]

Side by side shotguns are not regulated but are "laid up" according to the makers formula of what give the best results at normal shooting ranges for the variety of loads that may be used for that gauge. If your patterns are that close at 25 yds you are in a sweet spot don't mess with success.

 

[Britsmoothy]

Garbage.
Pedersoli don't regulate their doubles. They are set in a jig and that's it.
I've had five pedersoli doubles and only one shot to point of aim. The others I had to adjust.
I also adjusted two old breach loaders to suit my mount verses gun fit.
If you bevel the muzzle in a crescent such as a new moon on the same side of the muzzle the shot is going you will see it going the opposite way.

 

[denster]

Curious as to what is garbage?

 

[denster]

To the OP. Do not file on the muzzle of your gun. I have quite some experience with this as a younger man when I had seen it done on a few originals and proceeded to try it myself carrying it in some cases to the extreme. It had no effect whatsoever on moving shot patterns or slug point of impacts. The only thing it did was cause me to have to spend time filing muzzles back to square. Shotguns are not rifles where an out of square crown can have a significant impact on bullet impact because gasses are acting directly on the base of the projectile not so with a shotgun.
from your description I can draw two conclusions. Since the divergence is equal you have a good mount second you may be using a shot charge slightly heavier than optimum for the formula Pedersoli made their jig to accommodate which is generally in the mid range for normal shot charges for that gauge. You might need to drop back an 1/8th oz or a little more to have the R/L converge over point of aim. With side by sides it is a trade out between pattern density and convergence. Myself I will take density.
If you doubt this and want a graphic example go to the pattern board and with everything else the same drop your shot weight by a third and note what that does to convergence.
Here is what is happening with both side by side rifles and shotguns. The centerlines of the barrels are left and right of the centerline of the gun so when the right barrel is fired the recoil impulse is up and to the right and the opposite when the left barrel is fired. This is why the barrels which are parallel at the breech start to converge toward the centerline of the gun at the barrel key. It is interesting to see if you place laser pointers in the muzzles of a double where the centerlines of the bores converge. Depending on the weight of the gun it is normally 7 to 12 yds in front of the gun. The important thing though is where the muzzles are pointing when the projectile leaves the barrel and this is effected by the recoil impulse which is itself is most effected by charge weight.
I hope that was clearer than mud. In any case don't do damage to your gun anyone suggesting muzzle filing on a shotgun has either never done it or is good at kidding themselves.

 

[Brokennock]

To the OP. Do not file on the muzzle of your gun. I have quite some experience with this as a younger man when I had seen it done on a few originals and proceeded to try it myself carrying it in some cases to the extreme. It had no effect whatsoever on moving shot patterns or slug point of impacts. The only thing it did was cause me to have to spend time filing muzzles back to square. Shotguns are not rifles where an out of square crown can have a significant impact on bullet impact because gasses are acting directly on the base of the projectile not so with a shotgun.
from your description I can draw two conclusions. Since the divergence is equal you have a good mount second you may be using a shot charge slightly heavier than optimum for the formula Pedersoli made their jig to accommodate which is generally in the mid range for normal shot charges for that gauge. You might need to drop back an 1/8th oz or a little more to have the R/L converge over point of aim. With side by sides it is a trade out between pattern density and convergence. Myself I will take density.
If you doubt this and want a graphic example go to the pattern board and with everything else the same drop your shot weight by a third and note what that does to convergence.
Here is what is happening with both side by side rifles and shotguns. The centerlines of the barrels are left and right of the centerline of the gun so when the right barrel is fired the recoil impulse is up and to the right and the opposite when the left barrel is fired. This is why the barrels which are parallel at the breech start to converge toward the centerline of the gun at the barrel key. It is interesting to see if you place laser pointers in the muzzles of a double where the centerlines of the bores converge. Depending on the weight of the gun it is normally 7 to 12 yds in front of the gun. The important thing though is where the muzzles are pointing when the projectile leaves the barrel and this is effected by the recoil impulse which is itself is most effected by charge weight.
I hope that was clearer than mud. In any case don't do damage to your gun anyone suggesting muzzle filing on a shotgun has either never done it or is good at kidding themselves.

Hmm that's funny. We've had a few people here report success with carefully filling the muzzle.

 

[denster]

Hmm that's funny. We've had a few people here report success with carefully filling the muzzle.

And with all due respect they were at best kidding themselves. Think about it for a moment. What is the effect of filing the Muzzle? That on the side that is relieved gas is released earlier and moves the charge in the direction opposite of the relief. Now if this were a rifle that is what would happen as the gas would be acting directly on the base of the projectile. Not so with a shotgun as the last thing to leave the barrel is the over powder wad which at that point no longer has any effect on the shot charge. Even if you are using a plastic combination over powder shot cup wad it has no effect. There is a reason why this is not written up in any gunsmith manuals. If it was viable it would be.

 

[Britsmoothy]

We have another expert. I'm done.

 

[SDSmlf]

And with all due respect they were at best kidding themselves. Think about it for a moment. What is the effect of filing the Muzzle? That on the side that is relieved gas is released earlier and moves the charge in the direction opposite of the relief. Now if this were a rifle that is what would happen as the gas would be acting directly on the base of the projectile. Not so with a shotgun as the last thing to leave the barrel is the over powder wad which at that point no longer has any effect on the shot charge. Even if you are using a plastic combination over powder shot cup wad it has no effect. There is a reason why this is not written up in any gunsmith manuals. If it was viable it would be.

Interesting comment. If you go your copy of the Roy F. Dunlap’s book, Gunsmithing, pages 330 and 331 (I know you have all the gunsmith manuals), what does Dunlap say about off-shooting shotguns and ’removing metal from the inside of the bore at the muzzle, in the direction to move the pattern’? Don’t know how you missed his write up. Dunlop in his 1950 publication does not care for the modification, as in his opinion it enlarges the pattern in the desired direction, rather than shifting it. But it does center up the pattern. I was first shown this technique by my grandfather in the 1960s, and as best I remember from pattern boards, it worked. But my grandfather didn’t publish any gunsmith manuals, so can understand why you missed it. As a FYI, I have seen other references to this technique. In gunsmith manuals/books, imagine that. You will have to check your library on your own.

 

[toot]

one mans garbage is another ones treasure! we all don't have an endless / deep pocket.

 

[jlatz]

This is not the first time I have heard of the barrel regulation issue on a Pedersoli side-by-side. When at Friendship at the trap range I have heard talk about using files on the gun muzzles for regulation purposes. I have no experience with that. I have had good luck with old original side-by-side doubles. Either Belgian or British, they seem to pattern well.

 

[denster]

Interesting comment. If you go your copy of the Roy F. Dunlap’s book, Gunsmithing, pages 330 and 331 (I know you have all the gunsmith manuals), what does Dunlap say about off-shooting shotguns and ’removing metal from the inside of the bore at the muzzle, in the direction to move the pattern’? Don’t know how you missed his write up. Dunlop in his 1950 publication does not care for the modification, as in his opinion it enlarges the pattern in the desired direction, rather than shifting it.But it does center up the pattern. I was first shown this technique by my grandfather in the 1960s, and as best I remember from pattern boards, it worked. But my grandfather didn’t publish any gunsmith manuals, so can understand why you missed it. As a FYI, I have seen other references to this technique. In gunsmith manuals/books, imagine that. You will have to check your library on your own.

I have Dunlaps book and what he describes is an entirely different technique than is being referred to here. Dunlap describes removing metal from inside the bore not changing the muzzle profile as was being suggested here. As you stated he was not fond of the method believing it only enlarged the pattern rather than shifting it. So it did not accomplish the purpose.
I did not mean to start a controversy just trying to share my experience from some pretty extensive experimentation with side by side shotguns and regulating double rifles. Just seems to me that trying the change in shot charge weight to see the results might be a lot easier than filing away at the muzzles and if it doesn't work you have no damage to repair. They are your guns however so if carving half moons out of your muzzles pleases you grab a file and go for it.

 

[Griz44Mag]

For the last few days I have been attempting to get my (new to me) Trail Guns Armory side by side 58 to shoot both barrels to point of aim.
The sights are dual folding leaves, one directly behind the other and perfectly in line with each other and dead center on the center of the rib.
One is short the other tall - for 50 and 100 yards
These are not adjustable in any way.
AFter failing and many rounds later I decided to draw it up.
I clamped the gun down solid and fired 3 shots from each barrel. (They do group very nicely)
Right barrel hits a little high and 5" to the right.
Left barrel hits 4" low 2" to the left.
A 7" spread is not acceptable for hunting.
There is no way in hades to get these to shoot to a single point of aim with a single plane of sights.
Since I will be hunting with this - charges for right and left must be identical.
Drawing it out on graph paper and assuming the single set of sights - it is impossible to get them together with a single sight.
I have ordered a pair of Marbles #69WEH sights and will mount them in line with each other on the rib.
These are adjustable for both windage and elevation.
I will set the back one for right barrel, front one for left barrel and adjust as required for 75 yards convergence. This is the average hunting distance for deer where I go.
At 50 to 100 yards they will converge to minute of deer.
With the physical attributes of my gun, that convergence has elevation and windage both being corrected.
Say whatever you may on converging shots from double barrels but be aware - that convergent distance is fixed. If you go longer or shorter the point of convergence will change. How much it changes and if it matters for your usage - then pick the distance carefully.
Filing on the barrels (if it does work for you) will only fix the issue FOR A SPECIFIC DISTANCE. And that will be permanent.

 

[Britsmoothy]

For the last few days I have been attempting to get my (new to me) Trail Guns Armory side by side 58 to shoot both barrels to point of aim.
The sights are dual folding leaves, one directly behind the other and perfectly in line with each other and dead center on the center of the rib.
One is short the other tall - for 50 and 100 yards
These are not adjustable in any way.
AFter failing and many rounds later I decided to draw it up.
I clamped the gun down solid and fired 3 shots from each barrel. (They do group very nicely)
Right barrel hits a little high and 5" to the right.
Left barrel hits 4" low 2" to the left.
A 7" spread is not acceptable for hunting.
There is no way in hades to get these to shoot to a single point of aim with a single plane of sights.
Since I will be hunting with this - charges for right and left must be identical.
Drawing it out on graph paper and assuming the single set of sights - it is impossible to get them together with a single sight.
I have ordered a pair of Marbles #69WEH sights and will mount them in line with each other on the rib.
These are adjustable for both windage and elevation.
I will set the back one for right barrel, front one for left barrel and adjust as required for 75 yards convergence. This is the average hunting distance for deer where I go.
At 50 to 100 yards they will converge to minute of deer.
With the physical attributes of my gun, that convergence has elevation and windage both being corrected.
Say whatever you may on converging shots from double barrels but be aware - that convergent distance is fixed. If you go longer or shorter the point of convergence will change. How much it changes and if it matters for your usage - then pick the distance carefully.
Filing on the barrels (if it does work for you) will only fix the issue FOR A SPECIFIC DISTANCE. And that will be permanent.

It is reversible

 

[denster]

For the last few days I have been attempting to get my (new to me) Trail Guns Armory side by side 58 to shoot both barrels to point of aim.
The sights are dual folding leaves, one directly behind the other and perfectly in line with each other and dead center on the center of the rib.
One is short the other tall - for 50 and 100 yards
These are not adjustable in any way.
AFter failing and many rounds later I decided to draw it up.
I clamped the gun down solid and fired 3 shots from each barrel. (They do group very nicely)
Right barrel hits a little high and 5" to the right.
Left barrel hits 4" low 2" to the left.
A 7" spread is not acceptable for hunting.
There is no way in hades to get these to shoot to a single point of aim with a single plane of sights.
Since I will be hunting with this - charges for right and left must be identical.
Drawing it out on graph paper and assuming the single set of sights - it is impossible to get them together with a single sight.
I have ordered a pair of Marbles #69WEH sights and will mount them in line with each other on the rib.
These are adjustable for both windage and elevation.
I will set the back one for right barrel, front one for left barrel and adjust as required for 75 yards convergence. This is the average hunting distance for deer where I go.
At 50 to 100 yards they will converge to minute of deer.
With the physical attributes of my gun, that convergence has elevation and windage both being corrected.
Say whatever you may on converging shots from double barrels but be aware - that convergent distance is fixed. If you go longer or shorter the point of convergence will change. How much it changes and if it matters for your usage - then pick the distance carefully.
Filing on the barrels (if it does work for you) will only fix the issue FOR A SPECIFIC DISTANCE. And that will be permanent.

At the risk of starting another controversy sighting in a double rifle and determining a load where both barrels put their shots into a useful group with the same sight can not be done by strapping the gun down immobile. It must be done by the shooter actually shouldering the rifle the use of shooting sticks is OK so that the gun can recoil as it would when hunting. As I stated in one of my earlier posts when a double is shouldered and fired the right barrel will recoil up and to the right and the left will recoil up and to the left. Generally elevation is not a problem however the convergence of right and left is. As I recall the distance between bore centers at the muzzle is about 1&1/2 inches so an ideal situation would be no point of convergence but both barrels shooting parallels so at any distance the group centers would only be 1&1/2 inches apart. The ideal of course is not achievable. However if you have a load that converges at say 40yds the centers of the groups will only be 1&1/2 inches apart at 80yds. I would suggest using shooting sticks to shoot groups at say 35 yds and see where the R and L barrels print. As a rule if the R barrel is printing right and the L barrel printing left you will need to reduce projectile weight to get the degree of convergence desired. I have owned several Kodiaks and have always managed to find a load that would meet the British standard for a double rifle being 2R &2L into 4 inches at 50 meters.

 

[FishDFly]

Interesting reading, this is going to go into Favorites for future reading and use.

No way I am going to take sides in this discussion.

 

[Griz44Mag]

At the risk of starting another controversy sighting in a double rifle and determining a load where both barrels put their shots into a useful group with the same sight can not be done by strapping the gun down immobile. It must be done by the shooter actually shouldering the rifle the use of shooting sticks is OK so that the gun can recoil as it would when hunting. As I stated in one of my earlier posts when a double is shouldered and fired the right barrel will recoil up and to the right and the left will recoil up and to the left. Generally elevation is not a problem however the convergence of right and left is. As I recall the distance between bore centers at the muzzle is about 1&1/2 inches so an ideal situation would be no point of convergence but both barrels shooting parallels so at any distance the group centers would only be 1&1/2 inches apart. The ideal of course is not achievable. However if you have a load that converges at say 40yds the centers of the groups will only be 1&1/2 inches apart at 80yds. I would suggest using shooting sticks to shoot groups at say 35 yds and see where the R and L barrels print. As a rule if the R barrel is printing right and the L barrel printing left you will need to reduce projectile weight to get the degree of convergence desired. I have owned several Kodiaks and have always managed to find a load that would meet the British standard for a double rifle being 2R &2L into 4 inches at 50 meters.

No controversy here. I learn like all of us learn, from others and from personal experience. I have shot groups offhand and from a bag with this gun. I got results very close to what I got with the gun in a gun bench vice.
Right barrel high and to the right. Left barrel low to the left. This is a very clear cut indication that the barrels are not parallel.
I ramped loads in each barrel from 75gr to 110gr (factory designated max) Other than overall elevation, the right high-low and the left left-low pattern did not change. From your earlier comment on gun movement when a shooter holds the gun, I guess I hold pretty tight and shoulder in fairly solid because I see very little difference in my POI either way.
However - I can fix the gun and have it a workable piece for hunting and not have to worry about grinding hunks out of the muzzles. I see no way that more than 7" of spread at 50 yards can be corrected doing that. I also do not want to run different loads in each barrel. The hunt I have planned requires specific energy levels and calibers be used so I need both barrels to run the same powder load and ball and shoot to the point of aim. It took a lot of convincing to get permission to use a black powder muzzleloader in the first place. The rules put in place by the ranch owner is two shots at 75 yards in 10 seconds with no more than 4" spread.

 

[FishDFly]

"It took a lot of convincing to get permission to use a black powder muzzleloader in the first place. The rules put in place by the ranch owner is two shots at 75 yards in 10 seconds with no more than 4" spread."

Interesting rules, would you share some insight as to why?

I have heard of rules on certain animals as far as energy goes.

Just curious, what animal?

 

[denster]

I wish you the best of luck. One other suggestion is about gun mount. With a double rifle or shotgun you need to face the target square on not bladed. That is facing the target directly not left foot forward right to the rear. This is important so the gun has the same resistance to recoil when either the left or right barrel is fired. With the restrictions being placed on you I think your idea of one sight for each barrel is likely the way to go.

 

[Griz44Mag]

"It took a lot of convincing to get permission to use a black powder muzzleloader in the first place. The rules put in place by the ranch owner is two shots at 75 yards in 10 seconds with no more than 4" spread."

Interesting rules, would you share some insight as to why?

I have heard of rules on certain animals as far as energy goes.

Just curious, what animal?

Private ranch. It is closed to outside hunting. The ranch owner has never used or had anyone hunt with black powder on the property before. He has always said no to anyone that wanted to use one - he did not believe that black powder could have enough power to ensure an ethical kill. Both of his guides (his sons) have been telling him this for years.
One of his sons is one of my sons close friend. Nobody hunts the ranch unless someone in the family knows them, and deems them worthy.
I took one of the sons (along with my son) to the range with me on a PRS instructional trip and along with my $%#@#$ rifle, I took a 58 caliber BP rifle. After he saw it, shot it and believed it, we talked about just how effective it would be - on a buffalo. They only harvest 1 buffalo every 2-3 years. I have been waiting 9 years for this chance. Not this winter - but next winter - I will get my chance.