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Double Rifles, Single Shots & Combinations >> Double Rifles

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Classic416
.300 member


Reged: 08/09/06
Posts: 109
Loc: Brisbane, QLD, Australia
Technical Q. on DR's
      #63016 - 25/09/06 07:18 PM

I was wanting some technical info on Double Rifles (Not specific to any particular make, calibre etc) My understanding is that regulation of the barrels is where the art/science and cost comes in. Firstly, so as I'm not starting off with the wrong info, is regulation the aligning of the barrels so that at some point in space if a bullet is fired from each barrel simultaneously they would hyperthically collide? Assuming that is correct; is there an optimum distance that this should occur and if so is this dependant on a particular calibre and its designed use. Eg. a 470 nitro express might be regulated for 100m and a 375H&H for 200m?? Do the gun makers have standard distances for certain calibres and if so what are they? My understanding is that load development also takes on a critical part of the equation. Did/do the famous/expensive gun makers (Rigby, Holland and Holland, Purdy Beretta etc. no offence to all the other fine gun makers I haven't mentioned) develop an optimum load for their rifles and if so do they publish this info or advise the client what it is, or is it up to the client to work this out for themselves? I would imagine that like any other single barrel rifle, a double rifle performs better with one load than another. Actually, it must be more difficult to find this load for a DR as you are dealing with 2 seperate barrels. I know DR's are not designed for target shooting (this subject was brought up earlier) but you still don't want one barrel shooting totally different to the other. (once again, I guess this is where the expense comes in) Anyhow I am hoping for some info and perhaps some good discussion might occur. If these questions have been asked before, I appologise. I haven't had the chance yet to review every post on this Wonderful site. Thanks to all those involved.

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500Nitro
.450 member


Reged: 06/01/03
Posts: 7244
Loc: Victoria, Australia
Re: Technical Q. on DR's [Re: Classic416]
      #63021 - 25/09/06 09:06 PM


Classic416

Not all the cost comes in the regulation. ie Holland, Purdey and other high end european makers - the main cost is in the man hours to make the damn thing.

500 Nitro


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Marrakai
.416 member


Reged: 09/01/03
Posts: 3595
Loc: Darwin, Top End of Australia
Re: Technical Q. on DR's [Re: Classic416]
      #63022 - 25/09/06 09:15 PM

Classic416:
It is a commonly-held misconception that the flight-paths of bullets from each barrel of a double must 'cross' at some distance. In effect, they are regulated to shoot parallel. the reason for the confusion is simply that to shoot parallel, their bores must converge slightly in the rifle itself. This is because each barrel recoils slightly away from the other on firing, before the projectile leaves the muzzle.

A properly regulated rifle will form a useful composite group with the bullet strikes from the left barrel on the left side of the group, and those from the right barrel on the right side of the group, all the way to maximum possible range.

At the time these NE double rifles were built, standard 'factory' ammunition was available. They were simply 'regulated' during manufacture to shoot the factory ammunition of the day into a composite group, as described above.

Our challenge today, now that original factory ammunition is no longer available, and neither cordite powder nor in some cases correct bullet weight or shape exist, is to try to assemble handloads that emulate the original ammo well enough to 'regulate' in the old double rifles.

Hope this explains it....

--------------------
Marrakai
When the bull drops, the bullshit stops!
--------------------------------
www.marrakai-adventure.com.au


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Classic416
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Reged: 08/09/06
Posts: 109
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Re: Technical Q. on DR's [Re: Marrakai]
      #63029 - 25/09/06 10:27 PM

Thanks, yes that does explain it. It also means that some of the other questions I asked are no longer applicable. I also am aware that the cost of many fine DR's are because of the many, many hours taken to manufacture the rifle as well as the cost of exquisite timbers, engraving etc.

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NitroXAdministrator
.700 member


Reged: 25/12/02
Posts: 39896
Loc: Barossa Valley, South Australi...
Re: Technical Q. on DR's [Re: Classic416]
      #63048 - 26/09/06 03:17 AM

"Brand" name and reputation also would play a big part in the purchase prices.

--------------------
John aka NitroX

...
Govt get out of our lives NOW!
"I love the smell of cordite in the morning."
"A Sharp spear needs no polish"


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DUGABOY1
.400 member


Reged: 02/02/03
Posts: 1340
Loc: TEXAS USA
Re: Technical Q. on DR's [Re: Classic416]
      #63064 - 26/09/06 08:28 AM

In reply to:

I was wanting some technical info on Double Rifles (Not specific to any particular make, calibre etc) My understanding is that regulation of the barrels is where the art/science and cost comes in. Firstly, so as I'm not starting off with the wrong info, is regulation the aligning of the barrels so that at some point in space if a bullet is fired from each barrel simultaneously they would hyperthically collide?




The above statement is both right and wrong! By that I mean the regulation of the barrels is not the most of the expence of the building of a double rifle, though it is a major part. The hand fitting and stock makeing is where the"TIME" which is money is the major cost!

Your idea about the bullets colideing at some point if fired similtaniously, is true if both barrels could be fired EXACTLY similtaniously. because the rifle will recoil differently than when fired one barrel at a time. However, if they are fired one at a time, and the load is proper for the regulation built into the rifle they would not collide at any distance, and would not cross either. When fired one at a time the bullets fly paralell, to all practical ranges.


In reply to:

Assuming that is correct; is there an optimum distance that this should occur and if so is this dependant on a particular calibre and its designed use. Eg. a 470 nitro express might be regulated for 100m and a 375H&H for 200m?? Do the gun makers have standard distances for certain calibres and if so what are they?




It is not true, so that is out of the way! The regulated to "DISTANCE" has to do with the fileing in of the sights, only! The sights are aligned so the windage is set to point to the left/ right center of the composite group. Then only the elevation is filed into the first, of "STANDING" rear sight to it is dead on at the so-called regulation distance, as stated by the maker. If it has flip-ups for longer distances then they are filed in for the elevation needed for those distances, with no change in windage. If the load is proper for the rifle's regulation, then both barrels will form a composite group at each of those distances. IOW , shoot paralell!


In reply to:

My understanding is that load development also takes on a critical part of the equation. Did/do the famous/expensive gun makers (Rigby, Holland and Holland, Purdy Beretta etc. no offence to all the other fine gun makers I haven't mentioned) develop an optimum load for their rifles and if so do they publish this info or advise the client what it is, or is it up to the client to work this out for themselves?




Even today most common chamberings where factory ammo is available, the makers will regulate with a factory ammo that is most widely available. If it is not generally available, and he has to load it for the regulation of the rifle, then he will give that infromation to the customer. Or in some cases the customer can specify a load for the rifle to be regulated to, if it is within the pressure limits of the rifle.


In reply to:

I would imagine that like any other single barrel rifle, a double rifle performs better with one load than another. Actually, it must be more difficult to find this load for a DR as you are dealing with 2 seperate barrels.




This is true, and it applies to double rifles as well. Before any regulation is wasted the "IN THE WHITE" barrels are tested for consistancy, with each individule barrel with the load to be used. Occasionally, one barrel will not shoot the regulation ammo at all, or at least not acceptably, and that barrel may be changed out before further work is done on the regulation. The two, however, will never be exactly the same in group size, but must be accepted with in reasonable limits.


In reply to:

I know DR's are not designed for target shooting (this subject was brought up earlier) but you still don't want one barrel shooting totally different to the other. (once again, I guess this is where the expense comes in)




As my answer above, you are right that is part of the expence in a double rifle. However, double rifles are far more accurate than most think. I know long time double rifle owners who accept poor shooting loads simply because they think doubles are only good shortly off the end of the barrels. This is defintely not true! The flip up sights for down range were not put on the rifle for looks, if the rifle is loaded properly the rifle will shoot to those sights at those distances.


In reply to:

Anyhow I am hoping for some info and perhaps some good discussion might occur. If these questions have been asked before, I appologise. I haven't had the chance yet to review every post on this Wonderful site. Thanks to all those involved.




Duscussion is always better that the any crap fest tha happens sometimes on the net!
All of what I said above was really said b Marakai with fewer words, in a much better, and clearer verbage, but maybe I hit on something he might have missed, that will help you. In any event the only dumb question is one that isn't asked, but there are many dumb answers, I just hope mine wasn't the latter!

--------------------
..........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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Classic416
.300 member


Reged: 08/09/06
Posts: 109
Loc: Brisbane, QLD, Australia
Re: Technical Q. on DR's [Re: DUGABOY1]
      #63096 - 26/09/06 10:45 PM

Thanks DUGABOY1, that was most informative and interesting. I'm glad I did ask the questions.
Cheers, Ted


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unspellable
.300 member


Reged: 06/03/04
Posts: 187
Loc: Iowa
Anobservation o nregulationj [Re: Classic416]
      #63189 - 29/09/06 03:38 AM

The question of whether a rifle should be regulated to shoot parallel or to one point bothers me. I had until recently always heard that they were regulated to shoot to a single point.

Now let's consider a hypethetical rifle that will make dime sized groups at 500 yards from each individual barrel.

When fired, the rifle jumps toward wich ever barrel is fired, so that the position of each the muzzles at bullet exit is further apart than the distance beween muzzles when at rest. Lets say this distance is 1.5 inches. If regulated in parallel, then both barrels will be 1.5 inches apart at all ranges. But if regulated to one point at 100 yards, the two groups will converge going from muzzle to 100 yards. from 100 yards to 200 yards they will diverge back to the muzzle distance of 1.5 inches At 300 yards they will be 3 inches apart. Now 3 inches at 300 yards is quite good hunting accuracy and treading on the edge of bench rest accuracy. So I am not convinced that there is a practical difference in use. It does seem to me that regulating to a single point would be simpler. Also keep in mind, the two barrels will not produce the same velocity so there will be a difference in drop at extreme ranges.


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DUGABOY1
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Reged: 02/02/03
Posts: 1340
Loc: TEXAS USA
Re: Anobservation o nregulationj [Re: unspellable]
      #63227 - 30/09/06 03:31 AM

UNSPELLABLE, regulation is regulation, and the barrels are converging when you look through them! The barrel set clamped in a vice with the sights aligned on the bulls eye, at the so-called regulated distance, the right barrel will be looking at a point that is low, and on the LEFT of point of aim. The left barrel will be looking at a point that is low, and to the right of the point of aim. When fired the right barrel will recoil up, and to the right, to a point where the bullet leaves the muzzle. When the left barrel is fired, it will recoil up, and to the left to a point where the bullet leaves the muzzle. This is called barrel time. The convergance is adjusted so that when the right barrels bullet leaves the muzzle, it is in line with just right of the point of aim, and the bullet from the left barrel leaves the muzzle aligned with a point just left of POA, and with both aligned at the same elevation. That is the regulation of the barrels. They are regulated to shoot side by side, from muzzle to infinity. At this point the sights are not filed down to REGULATE THEM, for elevation, they are only centered between the bores of the barrles.

The distance you are speaking of has nothing to do with the convergance of the barrels, but simply adjusts the sights for elevation only, because they are aligned at a line that is exactly between the two barrel's bore centers.

The regulated distance has only to do with the standing rear sight, in relation to the front sight for elevation. You see a double rifle with multiple flip up sights has all the centers in line regardless of the distance they are cut (REGULATED)for, only the highth of the sight is cut differently.

If the barrels were made to CROSS at that distance, you would be right, but they aren't, this is the reason those rifles shoot to those sights all the way down range. With your idea of regulation, they would not shoot to those sights, past 100 yds for a rifle regulated to 50 yds. Every maker of FINE double rifles installs sights for down range shooting that are all in line with each other, no matter the range.



Example:

If each of the barrels is shooting a 1" individual group, then the barrels are converged so the bullets from each barrel will place the CENTER of that barrels group on it's own side of the POA, by 1/2", or side by side. IOW, PARALELL, the center of each barrles group 1/2" on it's own side will equal a composite group of 2" with the center of each barrel's individule group on it's own side of POINT OF AIM, no matter how far you shoot.

You are not alone in your thinking! It constantly amazes me at the well known gun builders of fine custom bolt rifles, and owners of fine double rifles who do not understand the regulation process, and so believe that barrels on doubles are regulated to cross at a given point in their flight. They make the mistake of trying to work up a load the will print the smallest composite group, rather that a load the will place each individule barrel group's center on it's own side of the POA. They, like you, think the sight regulation to a particular distance means both barrels to shoot to one hole, and that is why they have found when they work up a load the shoots one hole, the rifle continues to get wider apart as they go down range. That is because they are not shooting a regulating load, that load is usually a little high, as well. That load needs speeding up slightly, so the bullets leave the muzzles quicker, and it will shoot lower as well. If it has long range sights as well, this load will shoot to those sights down range!


This is the reason few people in any country, can regulate a double rifle, and even fewer in this country. because they don't understand regulation

--------------------
..........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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hoppdoc
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Reged: 02/03/06
Posts: 1791
Loc: Southeastern USA
Re: Anobservation o nregulationj [Re: DUGABOY1]
      #63229 - 30/09/06 04:37 AM

Superb explanation!! Kudos to Marrakai as well.Now regulation makes sence!

My ignorance is diminished substantially.Especially on how to adjust regulation in reference to how the gun is shooting!!

Thanks much!!

--------------------
An armed man is a citizen of his country, an unarmed man just a subject.

Edited by hoppdoc (30/09/06 04:39 AM)


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