Do different ammo loads affect double rifle accuracy?

Hammy953

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I'm new to double rifles, so I'm a bit ignorant of all the little nuances that come with such a rifle. In my research I've seen people talking about how each gun is regulated for a certain grain bullet and load. So my question is, if you use a different type of ammo will it affect the accuracy negatively in a noticeable way? I assume it will affect it to some extent given how physics works, but if it's negligible then I don't see why it's a problem. For example, I've seen people talk about using different loads for DG double rifles to hunt deer and other medium sized game. So I'm guessing that the effect can't be that bad. Well either that or they have multiple barrel sets with different regulations?

Like I said, I'm new to double rifles and trying to learn at least the basics before I start seriously looking at buying my first one. Better to at least have a basic understanding than go in blind afterall.
 
Honestly I believe it depends on many different factors and can vary from rifle to rifle & bullet to bullet & still again from load velocity.... figure in a force multiplier effect of different issues and you can see how things can get confusing quick and there are certainly people on here more versed than myself who will post previous link posts shortly.

As for my .470NE - It shoot both Woodleigh & Hornady bullets to the same point of impact with the same powder it was regulated for.
(3 red dots in a triangle gives me a more precise sight picture)
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RMaTU2C.jpg


Long story short... Velocity, bullet bearing surface and other variables are all at play in regards to accuracy and regulation loads.
 
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I'm new to double rifles, so I'm a bit ignorant of all the little nuances that come with such a rifle. In my research I've seen people talking about how each gun is regulated for a certain grain bullet and load. So my question is, if you use a different type of ammo will it affect the accuracy negatively in a noticeable way? I assume it will affect it to some extent given how physics works, but if it's negligible then I don't see why it's a problem. For example, I've seen people talk about using different loads for DG double rifles to hunt deer and other medium sized game. So I'm guessing that the effect can't be that bad. Well either that or they have multiple barrel sets with different regulations?

Like I said, I'm new to double rifles and trying to learn at least the basics before I start seriously looking at buying my first one. Better to at least have a basic understanding than go in blind afterall.
To answer your question , Yeah . In 1978 , I saw an August Francotte Sidelock Ejector in .458 Winchester Magnum . Regulated for Remington 510 Gr soft points and 500 Gr FMJ solids . Now , Remington 500 Gr FMJ solids for the .458 Winchester Magnum used to feature a much thinner cupronickel jacket than Winchester 500 Gr FMJ solids of the same caliber . So the owner came up with the bright idea to bring Winchester 500 Gr FMJ solids and Remington 510 Gr soft points with his Auguste Francotte double , to the Safari camp . Our white hunter had him zero in his rifles at camp , before all the serious hunting began . The Remington soft points produced incredibly tight grouping . The Winchester FMJ solids were producing a five inch grouping at less than 35 yards .

Sometimes , by way of a lucky coincidence , a double rifle might be able to produce accurate results with two brands of ammunition . Jim Bell ( the owner of the now defunct Brass Extrusion Laboratories Limited ) used to manufacture .470 Nitro Express ammunition which used to produce very accurate results in old British double rifles ( that were regulated for old ICI Kynoch cordite ammunition ) .
 
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To answer your question , Yeah . In 1978 , I saw an August Francotte Sidelock Ejector in .458 Winchester Magnum . Regulated for Remington 510 Gr soft points and 500 Gr FMJ solids . Now , Remington 500 Gr FMJ solids for the .458 Winchester Magnum used to feature a much thinner cupronickel jacket than Winchester 500 Gr FMJ solids of the same caliber . So the owner came up with the bright idea to bring Winchester 500 Gr FMJ solids and Remington 510 Gr soft points with his Auguste Francotte double , to the Safari camp . Our white hunter had him zero in his rifles at camp , before all the serious hunting began . The Remington soft points produced incredibly tight grouping . The Winchester FMJ solids were producing a five inch grouping at less than 35 yards .

Sometimes , by way of a lucky coincidence , a double rifle might be able to produce accurate results with two brands of ammunition . Jim Bell ( the owner of the now defunct Brass Extrusion Laboratories Limited ) used to manufacture .470 Nitro Express ammunition which used to produce very accurate results in old British double rifles ( that were regulated for old ICI Kynoch cordite ammunition ) .
Yesh, that's kind of crazy to think about. Like I know that all of these types of guns are extremely articulated work machines, but it's crazy to think such a minute difference can cause such a large discrepancy.

Well that answers one half of my question, but what about the other part? Does that mean that people who shoot multiple loads have to have multiple barrel sets made that are regulated differently? I'd imagine no one is having the guns re-regulated every time they decide to shoot a game animal that's smaller than a buffalo.
 
Yesh, that's kind of crazy to think about. Like I know that all of these types of guns are extremely articulated work machines, but it's crazy to think such a minute difference can cause such a large discrepancy.

Well that answers one half of my question, but what about the other part? Does that mean that people who shoot multiple loads have to have multiple barrel sets made that are regulated differently? I'd imagine no one is having the guns re-regulated every time they decide to shoot a game animal that's smaller than a buffalo.
That’s why I prefer bolt rifles . No complications ...

In all seriousness , double rifles are somewhat special purpose tools . The bulk of English double rifles aren’t made in calibers smaller than .375 Holland & Holland Magnum for this reason . Continental European hunters , however use double rifles quite a lot for the relatively smaller stuff . That’s why you’re going to find so many Continental European double rifles in calibers like 9.3x74 mm R , 8x57 mm JRS and 7x65 mm R .

Virtually all owners of double rifles will find one solid and one soft point load ( of equal weight and usually manufactured by the same brand ) which regulates to the same point of impact with both loads , and then they stick with it . They will only go through the trouble of reregulation , if the ammunition for which their double rifle was originally regulated , is no longer available to them . For example , all of the double rifles made the late 1960s and the 1970s , which were chambered in .458 Winchester Magnum . They were either regulated for Winchester or Remington ammunition . Since neither Winchester nor Remington manufacture .458 Winchester Magnum ammunition anymore , the owners of these double rifles are forced to have them reregulated out of compulsion .
 
When I purchased my Chapuis 375 H&H double rifle, second hand from a fine gun dealer in Phoenix,
the case included two targets marked with the description of ammo used to regulate the rifle: Federal Power Shok 300 gr. soft points and 200 gr. soft points, and the distance fired: 50 meters. These were the original documents from Chapuis that were still with the rifle in the case.
I understand that this is fairly standard practice for most double rifle manufacturers.
My experience in practicing with the rifle has been that it shoots most accurately with Federal ammo and I use Federal's 300 gr. Swift A-frames and Trophy Bonded Bear Claw with very good results. I tried Hornady and Norma and some others and the rifle was not nearly as accurate with those brands. Just my experience. Hope this helps answer your question.
 
It is possible with careful handloading to get a load to regulate. you might not win with every bullet or bullet weight. So a bit of a gamble, changing powder weights/powders/primers until you get a load that works. Some guys on the forum will probably give you some advice. Factory loads, I am guessing that different bullets will not regulate unless you are exceptionally lucky.
 
IMO every gun will have a different point of impact will a different bullet and/or a different powder or charge. I always sight in a scope to any new ammo. Some ammo is not as accurate as other ammo in different rifles. I had a 30-06 that loved federal green tips in 160 gr but hated Winchester silver tips, 1moa to 2.5moa. Night and day difference. And this is with one barrel. With double rifles this problem is maginified because you have two barrels trying to shoot to the same point of impact. Effectively doubling all the variables that go into an accurate rifle shot. Generally you do not re-regulate the double for each ammo and no you do not have different barrel sets for each ammo. Since doubles are primarily short range DG guns you regulate for an ammo you like and stick with it.

If you reload, you can get “lucky” with other bullets/powder combinations generally by trying to match similar weight bullets with velocity of the regulated load but that is not always a guarantee.
 
In my research I've seen people talking about how each gun is regulated for a certain grain bullet and load. So my question is, if you use a different type of ammo will it affect the accuracy negatively in a noticeable way?
Don't confuse "accuracy" with "regulation" -- they are two related but distinctly different terms. As MMAL mentions above, a change in ammunition (weight, velocity, bullet type) will affect the point of impact, but that is not the same as accuracy.

Either or both barrels can be "accurate" by itself -- consistently placing the projectile in the same area shot after shot. However in order to "regulate" properly, a bullet fired from each of those barrels must impact in the same vicinity. Two entirely different things.

Changes to ammo will very likely affect both accuracy and regulation of a double rifle.
 
I will answer your second question is that no people don't have a second set of barrels for a different load.
You should get a copy of "shooting the British Double Rifle" by Graeme Wright and read it cover to cover several times!!!!

With doubles everything is very different than what you know about regular rifles. Doubles are regulated at the builders with a specific load/maufacture. Some double will shoot most manufactures rounds well. Have a Chapuis 9.3x74 that shoots 286gr loads from Hornaday, Norma, S&B, Federal, and PRIVI. and a buddies exact same model will only shoot Federal well. When you start trying to reload for doubles it is a much different game.
 
When I purchased my Chapuis 375 H&H double rifle, second hand from a fine gun dealer in Phoenix,
the case included two targets marked with the description of ammo used to regulate the rifle: Federal Power Shok 300 gr. soft points and 200 gr. soft points, and the distance fired: 50 meters. These were the original documents from Chapuis that were still with the rifle in the case.
I understand that this is fairly standard practice for most double rifle manufacturers.
My experience in practicing with the rifle has been that it shoots most accurately with Federal ammo and I use Federal's 300 gr. Swift A-frames and Trophy Bonded Bear Claw with very good results. I tried Hornady and Norma and some others and the rifle was not nearly as accurate with those brands. Just my experience. Hope this helps answer your question.
Your Dealer wouldn't have been WLM & Sons by any chance would it?
 
I think I've heard that a SxS double rifle will shoot a laser low and to the left from the right barrel and low and to the right on the left barrel. It's the beginning of the recoil that moves the right barrel up and to the right to pull the bullet to the target. Same with the left barrel. So, changing loads and adding or subtracting recoil or changing the burn rate will change the point of impact.
 
I think I've heard that a SxS double rifle will shoot a laser low and to the left from the right barrel and low and to the right on the left barrel. It's the beginning of the recoil that moves the right barrel up and to the right to pull the bullet to the target. Same with the left barrel. So, changing loads and adding or subtracting recoil or changing the burn rate will change the point of impact.
Additionally, the velocity of the projectile (or time it spends in the barrel during recoil) is the biggest factor that moves POI from each barrel.
 
I've done business with them as well. Solid outfit, easy to work with.
 
Hammy,
Lots of good information in the above responses, so I will add only this:
As per AZDAVE above, I recommend a good Double Rifle book, The Double Rifle Primer by Cal Pappas.
IIRC, it mentions the fact that some DR that are already well regulated with one bullet and load will also regulate with another bullet and load. I tried this and BEHOLD, my Simson Suhl .405 DR that was well regulated with Hornady 300 grain bullets at 2250 fps also regulated 400 grain Woodleigh bullets at
2050 fps.
The 400 grain bullets at 2050 fps put that rifle up into the same performance range as the 450/400 DR.
 
I'm new to double rifles, so I'm a bit ignorant of all the little nuances that come with such a rifle. In my research I've seen people talking about how each gun is regulated for a certain grain bullet and load. So my question is, if you use a different type of ammo will it affect the accuracy negatively in a noticeable way? I assume it will affect it to some extent given how physics works, but if it's negligible then I don't see why it's a problem. For example, I've seen people talk about using different loads for DG double rifles to hunt deer and other medium sized game. So I'm guessing that the effect can't be that bad. Well either that or they have multiple barrel sets with different regulations?

Like I said, I'm new to double rifles and trying to learn at least the basics before I start seriously looking at buying my first one. Better to at least have a basic understanding than go in blind afterall.
I was thrilled to be able to consistently and very accurately take my 500 DR out to 100 yards off sticks today! All four shots within 3 inches using IMR3031 at 83 grains
 

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