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you will have to shoot the rifle to find out how bad things are or are not. This is best done from a standing rest and to do a good job you will have to do the shooting holding the rifle as close to how you would if hunting and not using the rest. The reason for this is that recoil starts as soon as the primer ignites the powder and the bullet starts to move. Since the centerline of the right barrel is off to the right and the left barrel off to the left of the center line of the rifle here is what happens. With recoil, the right barrel will move up and rotate to the right and the left barrel will do the oppsite. This is why a mechanical rest will not work very well for regulating. You will probably find that acording to a bore siter your barrels after regulating will look as if the will cross a bit. If you need some help feel free to call.

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450 366

I'm not sure this will help, but I measured two seperate 12ga. frames sleeved to 45-70 at the muzzle. One center to center was 1.025 and the other was 1. I checked a similar 12 still a shotgun and it was about .090 Neither rifle crosses at 100yd. but we had to spread the bbls.

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the double i built att the Gunsmithing school
has the barrels cross 20cm @ 100 meters.

/Roger

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lets see if i can explain this so there isn´t any missunderstandings,
when i sleaved the barrels, after soldering they crossed the centerline with 10 cm each (left barrel pointed 10cm to the right of C and the other way for the right.)

my DR was built on a BRNO 16 gauge sbs.
the measuremets att the muzzle is 24,8mm C - C
and att the breach it is 26,38mm C - C

the barrels are 596mm long

/Roger

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I do not buy that "last inch" statement of yours

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Ellis Brown's "Rule of Thumb" card came with his Good Ol' Boys Chinwag DVD, but I believe it is included in the new edition of his book. Someone should get his permission to post it here. If you follow his recipe for converting a shottie, weld the quarter-rib and loop the same distance from the breech, choose the same barrel-length, and are kissed on the dick by a fairy, you will probably find the measurements to be a good starting point.

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Offcourse this was only a question how much the barrels could cross, it wont be a way to regulate.
But it will be a whole lot easyer when nowing what distance from each other i should solder them together.

If some one did a rifle and found out that the barrels should be 2mm further apart, he would hate the job building himself a new set of ribs. I will be start looking for a fairy as soon as its getting dark.

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Andreas

"Yeas it kicks like a mule he said, but always remember that its much worse standing on the other end"

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Gentlemen, I think most here are giving the answers to two questions, one that was asked,and one that wasn't asked! IMO, the question he is asking is the amount of conversion of the barrels for a starting point for the physical regulation to be done with the least amount of correction! The other answer is being given is in regard to working up a load after the regulation is done! These are two distinctly different things! "REGULATION" is the physical manipulation of the barrel's conversion to shoot a known load correctly! While "WORKING UP A LOAD" which is mistakenly called "REGULATING" is finding a load the will shoot to the regulation of a finished rifle!

In this case, I think the poster is asking about Physically regulating the barrels. For a starting point for this opperation, one first needs to know the chambering to be used in this rifle. Because the weight, and recoil generated will have great effect on the first setting!

Once we have that the answers can be offered!

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Well i didnt say what caliber than i tought that if not i would get a whole lot of data concerning conversion. But now when its already lost its a 45-70 with 66cm barrels in a 4kg gun.

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All of these ideas and calculations are correct as are none of them! That is why the only solution is the tried and true, trial and error method. Every rifle is a bit different, hence every rifle will have a slightly different P.O.I. This is true even of rifles (and shotguns!) of the same make, weight, etc. Sure you can make some calculation maybe to get you close but it'd probably be just as easy to use a BIG target for those first shots and make your calculations for the next soldering according to where the initial P.O.I.'s fall on that large sheet of paper.

That said I do find the idea of assembling some data base of KNOWN convergence degrees (breech to muzzle) interesting, as said simply as a reference in the initial assembly. However, if this truely was useful I'm sure it'd be used by the established makers for many years and someone would know something of it. As yet that doesn't seem the case eh?

At any rate, given the very low numbers of such rifles to be produced by the home craftsman such an approach seems hardly worth the potential benefit. Lacking that is one of those fairies!

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I disagre the convergence should be a factor of recoil, elapsed barrel time and weight of the gun.
But you are right that its for the initial assembly. The finetuning could only be made on the range with a torch. But it wouldt take many rifles to see a pattern of convergence.
And if i was used to build doubles and had done so for 150 years i wouldnt need the use for a convergence table either.

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Andreas

"Yeas it kicks like a mule he said, but always remember that its much worse standing on the other end"

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I disagre the convergence should be a factor of recoil, elapsed barrel time and weight of the gun.
But you are right that its for the initial assembly. The finetuning could only be made on the range with a torch. But it wouldt take many rifles to see a pattern of convergence.
And if i was used to build doubles and had done so for 150 years i wouldnt need the use for a convergence table either.

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450_366, and Gentlemen, all regulators at all factories make a primary convergence, by educated guess. This, however, only a starting point, and will most times require several adjustments before the rifle is regulated.

When locking a set of double rifle barrels ( that are already regulated)into a vice with the sights lined up on a target at the distance engraved on the rear sight, what you will see is this!

The right barrel will be pointing to a point that is LOW, and on the LEFT of the POA of the sights, and the LEFT barrel will be looking at a point that is LOW, and on the RIGHT, of POA of the sights. To do this best is to chamber two empty cases, with no primers, and look through the primer hole down the barrel at the target but I suppose you could use a laser bore sighter, but it isn't needed for demonstration. This is because when the right barrel is fired, it rises UP and to the RIGHT. Also when the rifle's LEFT barrel is fired that barrel rises UP, and LEFT. When the convergence is right, the barrel being fired, will be pointing at the same place where the sights were pointing when the trigger was pulled. This is called barrel time. The barrels must be converging, because if they were parallel they would shoot high and wide.

Most folks are confused by this because there are two things that are called regulation, by the makers! ONE is the barrel's needed convergence, and the sights to point to the middle of the composite group of both barrels, and is simply the final adjustment of the iron sights.

Because the sights are REGULATED to a certain distance, it is assumed, by the un-schooled, that the shots cross at that distance, and this is not true. When a rifle is properly regulated, the center of each barrel's individual group is on it's own side of that composite group, and the sights are set half way between these two centers. The right side of the left barrel group, and the left side of the right barrel's group over lap giving you a slightly egg shaped composite group of both barrels, at the elevation marked on the iron sight being used.

The shots in a properly regulated barrel set, and with a proper load, do not cross at any distance, but shoot parallel regardless of distance.

If you tie a double rifle down so it cannot move, with the sights on the point of aim on a target at the distance engraved on the sight, the bullet from the right barrel will hit low, and left, and the left barrel will hit low, and right. This is because the recoil arch has been locked down so the rifle cannot move as the bullet travels down the bore to let the barrels point at the target on the POA when the bullet exits!

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..........Mac >>>===(x)===>
DUGABOY1, and MacD37 founding member of DRSS www.doublerifleshooterssociety.com
"If I die today, I have had a life well spent, for I've been to see the Elephant, and smelled the smoke of Africa!"

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