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NitroXAdministrator
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Does the time taken to shoot 2nd barrel affect regulation?
      #222070 - 21/12/12 03:41 AM

Does the time taken to shoot the second barrel affect regulation?

How long if firing two shots, do you take to shoot your second barrel on your double rifle?

A couple of questions for our members.

During my visit to Heym in Germany this year, an interesting conversation with one of the double rifle regulating smiths revealed something I had never heard before, nor seen on the net before.

Please discuss. I will explain more in a later post.

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John aka NitroX

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kuduae
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Re: Does the time taken to shoot 2nd barrel affect regulation? [Re: NitroX]
      #222074 - 21/12/12 04:43 AM

A well known fact in Germany. At firing one barrel of a soldered barrel assembly, be it a double rifle, drilling or combination gun, this barrel is heated and expands. This warming up measurably bends the barrels in the direction of the cold, unfired barrel. After a short time span the heat is dissipated to the still unfired barrel and the assembly straightens out again. In an open-sighted double rifle this movement is compensated as the front sight moves in the same way as the muzzles, so the effect of timing is unnoticable. As most German double rifles and dr drillings are scoped and a scope does not move with the muzzles, the time span between right and left shots has a marked effect on regulation. This is also the reason why most double rifles regulate either with open sights or with scope. See also Graeme Wright:"Shooting the British dr" page 188 of the 3rd edition. So a scoped dr has to be fired at the same sequence, right-left, and at the same timing, say 10 seconds, as the rifle was regulated. In practical hunting this timing necessity most often goes unnoticed, as the second barrel is used only at running game at short range or in case of an emergency when the animal does not drop properly at the first shot. The knowledge of this time to regulation effect is a reason behind the continental design of double rifles with ugly, usoldered barrels that are independent of each other.

Edited by kuduae (21/12/12 04:53 AM)


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xausa
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Re: Does the time taken to shoot 2nd barrel affect regulation? [Re: kuduae]
      #222120 - 22/12/12 01:08 AM

Axel,

Would the over and under configuration of many continental double rifles not tend to minimize this problem?


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NitroXAdministrator
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Re: Does the time taken to shoot 2nd barrel affect regulation? [Re: xausa]
      #222122 - 22/12/12 01:29 AM

As Kudae mentions, in the regulation of a double rifle, the first shot warms and expands the first barrel, this has a stretching affect on the second barrel. The quantification of this depends on the amount of time taken to make the second shot.

Paco, the German gunmaker at Heym who one of the principal gunmakers responsible for regulating their double rifles, says he regulates for a period of seven seconds. A longger period will cause the barrels to spread further.

It is interesting to read Kudae's comments re open sights, vs scopes, with scopes there is greater influence of the stretching of the barrels during warming increasing barrel spread, compared to open sights.

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NitroXAdministrator
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Re: Does the time taken to shoot 2nd barrel affect regulation? [Re: xausa]
      #222123 - 22/12/12 01:30 AM

Quote:

Axel,

Would the over and under configuration of many continental double rifles not tend to minimize this problem?




There would still be barrel spread, with the time factor, except it would be vertical rather than horizontal.

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John aka NitroX

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xausa
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Re: Does the time taken to shoot 2nd barrel affect regulation? [Re: NitroX]
      #222133 - 22/12/12 02:04 AM

Quote:

There would still be barrel spread, with the time factor, except it would be vertical rather than horizontal.




True, but the difference between the point of impact of the second shot with iron sights and with scope sights should be minimized. Also, in many instances vertical dispersion is less of a problem than horizontal. For instance, if one misses a heart shot taken broadside vertically, it will still catch the lungs or break a leg. The same shot, deviating horizontally, will result in a gut shot or a clean miss.

Of course, with shots taken at close range, in rapid sequence, the point of impact deviation in either case would hardly be noticeable. I certainly never noticed it shooting elephant and buffalo with my scope sighted over and under .458 WM.


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NitroXAdministrator
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Re: Does the time taken to shoot 2nd barrel affect regulation? [Re: xausa]
      #222401 - 27/12/12 08:55 PM

Quote:

Quote:

There would still be barrel spread, with the time factor, except it would be vertical rather than horizontal.




True, but the difference between the point of impact of the second shot with iron sights and with scope sights should be minimized. Also, in many instances vertical dispersion is less of a problem than horizontal. For instance, if one misses a heart shot taken broadside vertically, it will still catch the lungs or break a leg. The same shot, deviating horizontally, will result in a gut shot or a clean miss.

Of course, with shots taken at close range, in rapid sequence, the point of impact deviation in either case would hardly be noticeable. I certainly never noticed it shooting elephant and buffalo with my scope sighted over and under .458 WM.




Interesting to look at from this perspective, where a higher or lower shot may still be effective where one to the side may not. Often true for broadside and also frontal shots.

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John aka NitroX

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bonanza
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Re: Does the time taken to shoot 2nd barrel affect regulation? [Re: NitroX]
      #222409 - 28/12/12 12:12 AM

I think it would be minuscule. Lost in the variance of open sight shooting.

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granhaven
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Re: Does the time taken to shoot 2nd barrel affect regulation? [Re: NitroX]
      #222562 - 30/12/12 01:18 PM

NitroX

Shooting my Merkel BBF 7x65R 12/70 at regional Polish shooting competitions, where one of the diciplines is 100 Meters standing Roebuck with a series of 10 shots within 10 minutes, I allways had to compensate for shot number two with 10 centimeters under the target, shot number 3 at 18 centimeters under, shots number 3 to 10 still 18 centimeters under. This does indeed complicate shooting. the waiting time untill the barrels have come back is up to 15 minutes.

Normal rythm in shooting would be roughly 40 seconds or so.

Shooting a double rifle in a driven hunting situation is a different setup, the time difference will be in the range of 1 to 2 seconds for a small caliber like 7x65R and a little more for a 375Flanged.

To me 7 seconds between shots when regulating seems quite long, boars running at 10 meters / second will have covered 70 meters by then and be looooong gone in the forest. I do not have a direct meassure of the upper barrel movement over time but it cannot be neglected and should be considered when regulating and testing ammunition.

To discuss how well a double rifle regulates at 200 meters, paralele or crossing is for me a purely academic discussion, 50 meters is quite an acceptable distance. If they are an inch or two part that will be all I can whish for.

regards, Peter Frost Hørlyck


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NitroXAdministrator
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Re: Does the time taken to shoot 2nd barrel affect regulation? [Re: granhaven]
      #222568 - 30/12/12 01:39 PM

Quote:

To me 7 seconds between shots when regulating seems quite long




Peter

Thanks for the comments. Interesting.

I believe the 7 seconds was the standard he uses. He said a longer period could be used if the client wanted or presumably shorter. I believe the longer the period before the second shot, the wider the grouping between the barrels was.

When shooting the rifles, I took a lot longer shooting the second barrel one time, and the impact was considerably wider, which was claimed to be the longer gap time. The gap time had already been discussed previously btw. Myself I thought it was merely my shooting.

--------------------
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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