I was looking up information regarding the .375 Flanged Magnum in the Barnes reloading manual and I read this (emphasis added):

quote:

Some have claimed you can use the same load data in the Flanged Express and the belted H&H, but in double rifles at least, the loads must be compatible with factory loads or the bullet impact can vary considerably. Ideally, the loads from each barrel will converge at 60 yards, and the seemingly simple task of regulating the barrels with more than one or two loads can turn into a nightmare if bullet weights and respective velocities stray much from factory standards.

In the .450-400 3" section it says:

quote:

The main objective, though, with a double rifle is to get it regulated so both barrels will shoot under 2 inches at 50 yards .

What is the correct standard for regulation?

Neither of the quotes you posted. They are both over simplifications.

True regulation has both barrels shooting parrell to infinity, and with both at the same elevation too.

My .500 NE runs 1 inch at 50 yards as does my 450-400. My Rigby .450 NE shot 1.9 inches at 100 yards. Some do and some don't.

Dutch

If a regulated double rifle shooting a regulating load the CENTERS of each barrel’s individual group never cross at any range. If PERFECTLY regulated the centers of each barrel’s individual group will remain on it’s own side of the aiming point one half the distance between the CENTERS of the bores of both barrels and dead on for elevation at the distance engraved on the standing rear sight. With proper regulation both barrels will form a slightly egg shaped composite group of both barrels with the aiming point in the middle between the two CENTERS of the individual groups.

Of course this is in a perfect world, a seemingly impossible thing to find. However if the CENTERS of both barrel’s groups cross then the load is too fast, if the centers are wider than half the distance between the centers of the bores of the barrels the load is too slow.

If all shots form a tight one ragged hole on the target then the rifle is crossing at that range, and the rifle is not regulated properly.

The best way to find what the rifle is doing is to fire four shots, each from a cool barrel from each barrel on separate identical targets. Then find where the CENTER of each barrel’s individual group in relation to the aiming point on each target. What you want to move is NOT the bullet holes but the centers of each barrel’s individual group to half the distance between the centers of each barrels bore with the aiming point half way between those centers.

IOW parallel with the aiming point half way between them!

It may seem impossible for barrels that are fixed to converge to shoot parallel, but the barrels have to be fixed converging so they will shoot side by side. This is because when either barrel is fired, the rifle rises UP, and AWAY from the other barrel. While the barrel is rising and moving away form the other barrel there is this thing called BARREL TIME, which is the time the bullet is traveling down the bore till it exits the muzzle at just the point where it is pointing on it’s own side to where the sights were when the trigger was pulled. The barrels must be CONVERGING so they will shoot PARALLEL!

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What Mac said! Mine seem to converge at some point.

In other words--

Its Black Magic-------

Mac37 is describing a perfect world. Unfortunately, most (if not all) double rifle manufacturers adjust bbls. to cross at a given distance (FN-Browning = 80 m, others opt for 25, 50, 60 m, etc.). I would love to have my 9,3x74R double keep 2x2 shots within 2 cm at 50 m, 4 cm at 100m, and so on... Unfortunately, with all loads, my bbls. do cross "somewhere" between 50 and 100 m.

Here are a few targets shot at 50 m with different 286 g. bullets.


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quote:

Originally posted by Andre Mertens:
Mac37 is describing a perfect world. Unfortunately, most (if not all) double rifle manufacturers adjust bbls. to cross at a given distance (FN-Browning = 80 m, others opt for 25, 50, 60 m, etc.). I would love to have my 9,3x74R double keep 2x2 shots within 2 cm at 50 m, 4 cm at 100m, and so on... Unfortunately, with all loads, my bbls. do cross "somewhere" between 50 and 100 m.

Andre
DRSS

3shots do not make a group, they show point of aim or impact.
5 shots are a group

First off, let me say everything I have to say about regulation here is for a S/S double rifle , but the same rules work for O/U doubles as well with some modification of where the center of composite group are concerned. The proper composite group for the Over/Under will be the bottom barrel being slightly below the top barrel with the top barrel centered on the aiming point, with the composite group of both barrels being slightly egg shaped along a vertical line through the group.

The bold print in your post above doesn’t mean what you think it does ! Those distances are how the sights are cut, to zero the sight on the CENTER of the composite group at that range for elevation and windage at the distance engraved on the standing rear sight. Do you think a double rifle with multiple flip-up sights for down range distances are simply on the rifle for decoration? They are not!

If you will look at those flip-ups you will see that the center lines of each sight are all in line, with the only difference being the elevation. If the rifle was regulated to cross at the distance engraved on the standing rear sight then the down range sights would be useless as the rifle with the sight cut for your 80 yds to cross the barrels would cross more the farther it went down range.
The maker's habit of using the word REGULATED to state how the standing sight is cut for windage and elevation at a given range leads folks to think that means the rifle should make a one ragged hole on the point of aim at that range. If that was what is meant by that statement the rifle WOULD be crossing at that distance, but that is not the case. All that pertains to is the sight is cut to be CENTER of the COMPOSITE group of both barrels along a line for elevation at that distance.


Let me start with your byline about what constitutes a proper group!

The only reason 5 shots was used to form a group was because most bolt action rifles carry 5 rounds. The thought was to find how tight the group would remain from a whole magazine load this is because of how the bolt magazine rifle is used in the field.

When finding a load for the regulation built into a double rifle an individual barrel group is 4 rounds all fired from a cool barrel to find the CENTER of each barrel's individual group in relation to the aiming point of the sights. This is because of the way a double rifle is used in the field.

A double rifle is rarely fired more than four shots total, two from each barrel. The first shot from each barrel being from a cool barrel. The next two follow-up shots being from slightly warm barrels.

Because the original first two are fired from cool barrels then to find proper group CENTERS the starting point for regulation is four shots from each barrel all fired from cool barrels.
Once the centers of each barrel's group is found then one knows which way to move the CENTERS of each barrels group in relation to the aiming point, and to each other. It is those CENTERS of group that you want to move not bullet holes.

The reason you think the makers regulate the barrels to cross is because some of your bullets from each barrel spill over into the group of the other barrel, but the CENTERS of each barrel's individual group remain on it's own side of the aiming point on the target.

Lets say each barrel is shooting a one inch group at 100 yds, and the centers of each barrels individual group remains 1/2 inch on it's own side of the aiming point on the target, some of the RIGHT SIDE of the LEFT barrel's group will spill over into the LEFT side of the RIGHT barrels group and vice-versa. The centers of each barrels group of a properly regulated double rifle will never cross.

The shots from both barrels is what form the composite group for the rifle!

Your groups are very good, but because some of the bullets cross over into the other barrels group doesn't mean the rifle was regulated to cross at any distance. Again it is the centers of each barrel's individual groups in relation to the aiming point is how one tell if the3 rifle is regulated properly, or the load he is using is a proper load for regulation of the rifle. This is why when working up loads for a double rifle the best thing to do is use two target, one for each barrel, and fire all shots from cool barrels, then find the CENTERS of each barrel's individual group in relation to the aiming point on the target.

Because the sides of each barrel's group spill over, one must find the CENTERS of each barrels group, or he will never know exactly how well his rifle is regulated.

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The correct answer is whatever the customer specifies. If they want them to converge at 100yds that's what I try to achieve as close as possible. If they dont specify I get it shooting parallel or slightly closing at 50yds. Slightly closing is always better than slightly opening. Concluding, a gun shooting either of the two ways above will still be adequate for anything within 200yds, which is a long way concerning double rifles.

Also note a gun that converges at 100 can most likely be opened up with handloads to converge at an even greater distance or shoot parallel.

quote:

Originally posted by Aaron Little:
The correct answer is whatever the customer specifies. If they want them to converge at 100yds that's what I try to achieve as close as possible. If they dont specify I get it shooting parallel or slightly closing at 50yds. Slightly closing is always better than slightly opening. Concluding, a gun shooting either of the two ways above will still be adequate for anything within 200yds, which is a long way concerning double rifles.

Also note a gun that converges at 100 can most likely be opened up with handloads to converge at an even greater distance or shoot parallel.

.............................................................Absolutely perfect!

First of all, Mac is 100% correct, in that a perfectly-regulated double will launch a left and a right on parallel tracks, with no convergence at any range. An integral part of the regulation process is minutely bending the last 6 or 8 inches of the barrels in order to achieve this.

The only exception I would take with Aaron's post is that a well-regulated side-by-side, my experience, can easily be a 300 yard rifle in the hands of a shooter who has used it enough to have skill with, and confidence in it. I killed a Sable bull 3 years ago at a ranged 208 yards, with my .450 #2, both shots landing within 3 inches of each other. Had the range been 300 yards, I would still have been able to make that shot, given, of course, the same solid position and all the time in the world to settle in.

MacD37, I absolutely agree with you, as long as we talk about the same context, which at times strays off course… It seems to me that you refer to "African" rifles (often of large calibre) with multiple leaf sights and meant to be shot at varying short to half-far distances while stalking heavy/dangerous game, hence the importance of keeping both barrels trajectories on a parallel/vertical course, all along the bullets paths . The immense majority of these rifles were (are ?) manufactured in UK, based on centuries old colonial experience.

Not so in continental Europe. Apart from rare instances when they receive an very special order from a fortunate hunter planning an African safari, all double rifles built by European gunmakers are destined to drive hunting big game (Wild Boars, Red Deer, Roe Deer, Fallow Deer, Mouflon, Moose, etc.). Drive hunting with drivers and hounds means all shots will be running and in cover. Shooting is (very) fast and always < 100 meters (109 yds), with 80% of the shots taken between 10 and 30 meters (11-33 yds).
This pic represents a typical situation : a speeding Boar with hounds on its tail and jumping a narrow trail.


Believe me, you'd better be prepared to shoot as soon as you hear dogs closing in and/or twigs cracking…

Considering these shooting conditions, there's never more than one single rear sight leaf and most hunters opt to use a "battue" scope anyway (1,25-4x24) with a highly visible/illuminated reticule
(see pic).


For the same reason, gunmakers like FN-Browning, Beretta, Chapuis, Franz Sodia, Merkel, Chapuis, Lebeau-Courally (arguably one of the finest gunmakers on earth, including H&H, Purdey, etc.) choose to regulate the barrels to shoot together at one distance (50-80 meters / 55-88 yds), the consequence being that respective trajectories do cross somewhere downrange. To illustrate the regulating process, I've translated from French this excerpt out of the official specs book of FN-Browning :

"…A double –rifle is regulated when 4 shots are placed in the target, at 80 meters (88 yds), with 5 cm (2") spreading and 4 cm (1.6") convergence, without divergence. This implies that:

• 2 cartridges are shot from each barrel ;
• the impacts of the same barrel. must be contained in a circle of 5 cm (2") diameter, whose center is their mean point (i.e : half the distance between the center of the impacts);
• the vertical spreading between the mean point of shots from each barrel must not exceed 4 cm (1.6");
• crossing of bullet trajectories from the 2 barrels takes place behind 80 meters (88 yds).

NB : in others words and to keep it simple, the 2x2 (widest, not CTC) shots must be contained in <9 cm at 80 m / 3.5" at 88 yds (my original factory target measured 6 cm/2.4" , measured from widest points).

Being how I am, I had the rifle re-regulated later on until it kept borh barrels in the same hole...
Further, out of the 2 videos posted above (I'll lose no time with the Sabatti one, which is nothing but a bad joke. To our friends owning a sweet shooting Sabatti, I'll advise to nurse and cherish it as they house a rare bird, indeed…), I noticed that the esteemed Westley Richards Cy. follows just the same regulating process as FN-Browning. And it is also stated that :

"…Regulating the barrels of a rifle means adjusting/regulating the 2 barrels of a rifle to shoot to the same point of aim at a given distance …", which is further illustrated by the final target picture showing both barrels shooting together in a single group.

Here's another example I dislike : a friend's Chapuis Orion as it came from the factory ;



This being said, I'd be enchanted to meet a gunmaker like Aaron Little, prepared to agree to his customer's wishes and willing to regulate both barrels S/S ou O/U very close together and shooting the same, without crossing, at all distances. I personally would like that but have had all my requests turned down by our master gunmakers, on the grounds this was not the proper way they were taught (BTW, try to convince one of them to glass bed or full float the barrel of a bolt action rifle and you'll get the same reaction about "sloppy" woodworking. And then, I won't mention synthetic stocks which will get you branded as a heretic…).

quote:

Originally posted by Sean Russell:
In other words--

Its Black Magic-------

No, Black Magic would be having the barrels cross at 60 yards AND converge again at 100 yards.

quote:

Originally posted by Grenadier:

quote:

Originally posted by Sean Russell:
In other words--

Its Black Magic-------

No, Black Magic would be having the barrels cross at 60 yards AND converge again at 100 yards.

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