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Double Rifles, Single Shots & Combinations >> Double Rifles

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Brian
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Reged: 03/02/05
Posts: 41
Loc: NY (Delaware County)
Double rifle zeroing quandry/issue
      #272184 - 26/10/15 11:24 AM

Let me preface this by saying that my accuracy expectations are based on my experiences with my Chapuis 9.3x74R. That rifle spoiled me; it put 2 pair into 1 1/2” at 100 yards all day long. So, that is my gold standard to judge by. Maybe that is wrong but it’s my baseline to compare against.
Which way to zero a double rifle with what I call only fair accuracy. The factory standard for the company that built this rifle is 10 CM at 100 M so its within factory specs. I have been shooting double rifles for 15 years now and am not an expert but no beginner either. There is always more than one way to look at a problem and I am asking for opinions and insight to possible similar situations and solutions you may have come up with.

I am using Norma 150 Gr. Factory loaded 7x57R ammunition. I have also tried Privi 139 and get similar results. Scope factory mounted and regulated (Leupold 2x7 VX-R scope) in EAW mounts.
Shooting with rifle on my hands, my hands supported with a sandbag in front and up against my shoulder at rear. Fore end is gripped by my hand.

My 7x57R double rifle shoots 2 pair into about 3 1/2-4 inches at 100 yards. Each barrel puts its two shots to its respective side of the bull. Right barrel to right side etc. each barrel puts two shots within an inch of each other.

So, here is my question.
I could zero with a center hold and both barrels will hit 1 Ύ”- 2” to either side of center and just accept 4 MOA group average. Or I could zero with the right barrel shooting point of aim/point of impact and left barrel would be 3 ½“-4” to left of that. With this zero I have first shot where I could be precise as hell and second shot most likely game would be moving then. and then there is the issue of threading a bullet between trees in a tight shot.
At 50 yards or less, either zero would be good enough regardless, it is only when getting out to 100 or more where it becomes more critical for good hits. And it is the longer distance that you need the least amount of error.

I am using this primarily for whitetails. At maximum this is a 200 yard rifle. Most of my shots are 50-100 yards but I do have a few meadows I can easily reach out to 200 from a stand. So, what would you do. There are pros and cons to each method.

What are your thoughts.

Edited by Brian (27/10/15 10:18 AM)


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MikeRowe
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Reged: 23/11/11
Posts: 478
Loc: Arkansas, USA
Re: Double rifle zeroing quandry/issue [Re: Brian]
      #272186 - 26/10/15 11:48 AM

It sounds like you have a very accurate rifle, if the individual barrels put their shots within an inch of each other.

The current regulation is a result of whatever lot of ammunition the rifle was regulated with on that particular day. Changes in ammunition specs, powder lots and such will change the velocity and other characteristics over the years.

To get the results you desire, a little handloading might be in order. You're very close now, and with a little work, you should have a rifle that'll put them all in 1 1/2".

I would not want to accept average with this rifle.


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mchughcb
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Reged: 21/02/14
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Loc: Victoria, Australia
Re: Double rifle zeroing quandry/issue [Re: MikeRowe]
      #272188 - 26/10/15 04:46 PM

Apart from selling it and buying a blaser S2 or BBF97 which allows you to regulate with an allen key I'd go with option 2. The reason is this. You intend to shoot mainly from a stand and stalking up to 200 yards. You should have the luxury on not having to take a running shot most of the time. If you are like me, you don't want to mix right and left round loads. Therefore the right barrel should be hitting the target spot on at 200 yards which is probably 2" high at 100 yards. The second shot is only a back up and for running game at 100 yards or less and the being 4" off isn't going to matter.

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tah
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Reged: 19/10/15
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Re: Double rifle zeroing quandry/issue [Re: mchughcb]
      #272195 - 26/10/15 09:24 PM

Your double has good accuracy. I agree that you should zero with the right barrel and be confident that your first shot hit where you aim. You might get it to group closer by handloading, trying lighter bullets or heavier charge (if possible). I got my Chapuis double in 9,3x74R to group better when I tried 250 grains bullets instead of 286 grains (Swift A-frame).

Tore


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Well_Well_Well
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Reged: 03/01/07
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Re: Double rifle zeroing quandry/issue [Re: tah]
      #272221 - 27/10/15 07:19 AM

Brian,

I agree with Mikerowe.

You probably only need another 25-50fps to bring those impact points together, which may retain the inherent accuracy of each barrel.

Hand loading will allow you precise control of your loads as well as getting specific performance from your projectiles.


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NitroXAdministrator
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Reged: 25/12/02
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Re: Double rifle zeroing quandry/issue [Re: Well_Well_Well]
      #272231 - 27/10/15 05:38 PM

Yep try handloading. A but more velocity might bring the groups together.

I assume you are shooting a Right/Left, a Right/Left, not shooting each barrel individually.

And also shooting each two barrel group with reasonable speed, ie only a few seconds in between shots eg say seven. Though I would guess in theory, if the barrels are warmer, ie a shorter time period I would think the expansion would push the barrels apart more.

I would have a lot of trouble accepting a four MOA "group" in a small double calibre such as 7mm. Irrespective of whether each barrel is shooting well.

Quote:

The factory standard for the company that built this rifle is 10 CM at 100 M so its within factory specs.




What is the brand? I can't see it mentioned.

--------------------
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"


Edited by NitroX (27/10/15 06:13 PM)


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Brian
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Reged: 03/02/05
Posts: 41
Loc: NY (Delaware County)
Re: Double rifle zeroing quandry/issue [Re: NitroX]
      #272238 - 27/10/15 10:18 PM

Chapuis Series 3

--------------------
Brian

LTC, IN
Back from Afghanistan
Life Member A.H. Fox Gun Collectors Assoc.
Endowment Member NRA
Delaware County, NY


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Rell
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Reged: 03/12/04
Posts: 642
Loc: Oyster Bay, NY, USA
Re: Double rifle zeroing quandry/issue [Re: NitroX]
      #272239 - 27/10/15 10:19 PM

Not at all sure if this helps but I went through similar angst with my 7x65r. 3.5 inch groups at 100m. I have a 2-12x42 VX6 mounted on it.

I thought maybe the rifle was regulated at 150m or 200m. I shot groups at 150m and the groups where around 2.5 inches for 2R and 2L. At 200m I was about 2 inches. I did not have a 250m stand but at 300m it was about a 4.5 inch 4 shot group.

I mostly hunt bushbuck and pigs with this and a shoulder hold just on the crease half way up the body is lethal out to 300m.

With your scope I would try shooting longer distance and see what happens.

--------------------
450-400, 9.3x74r and 7x65r.


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DarylS
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Reged: 10/08/05
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Re: Double rifle zeroing quandry/issue [Re: Rell]
      #272247 - 28/10/15 05:01 AM

Rell - shooting 1 1/2MOA to 300 with a double sounds like exceptional accuracy to me. There are lots of factory $1,100.00 bolt action'd rifles that will not do that with factory ammo and some won't even with handloads.
Indeed, there are lots of hunters who can not shoot better than 4 1/2" at 100 meters. We see them every year at the range.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V


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Rell
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Re: Double rifle zeroing quandry/issue [Re: DarylS]
      #272267 - 28/10/15 11:16 AM

I'm thrilled with the 300m accuracy but if I'd stopped at 100m with 3.5 inch groups I would have been an unhappy camper.

Double rifles are frikin voodoo but I am done with 100% done with factory $1,100 rifles with no soul.

--------------------
450-400, 9.3x74r and 7x65r.


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Brian
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Reged: 03/02/05
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Loc: NY (Delaware County)
Re: Double rifle zeroing quandry/issue [Re: Rell]
      #272516 - 02/11/15 10:30 AM

UPDATE: shot rifle today with Norma 150 Gr and Privi 139 gr.
the Norma still shoots terrible. The Privi however shoots a whole lot better Good enough tat I am zeroing both barrels and the phot shows a group of 3 rights and 3 lefts at 100 yards. center of target as aiming point. I then shot it at 200 yard with that zero and it was about 6" low and about 6in. group but well centered. we are good to go until I can start developing a load for it.


--------------------
Brian

LTC, IN
Back from Afghanistan
Life Member A.H. Fox Gun Collectors Assoc.
Endowment Member NRA
Delaware County, NY


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DarylS
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Re: Double rifle zeroing quandry/issue [Re: Brian]
      #272518 - 02/11/15 11:36 AM

I'd say so. I would expect the top 3 (left?)to be close to ON at 200yards. Perhaps that is as it should be?
Excellent individual barrel grouping with those light bullets.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V


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NitroXAdministrator
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Re: Double rifle zeroing quandry/issue [Re: DarylS]
      #272538 - 02/11/15 11:56 PM

Just an idea, how does the rifle 'regulate' with the scope removed using the original ammo or the ammo the factory regulated it with.

I know you probably want to use the scope, just interested in the results.

--------------------
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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aromakr
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Reged: 20/04/11
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Re: Double rifle zeroing quandry/issue [Re: NitroX]
      #272559 - 03/11/15 02:46 AM

Brian:
Some food for thought! I had a similar problem with my 9.3X74R, i.e. one barrel grouping above the other. I changed from a spire point bullet to a round nose and they came together. I would give that a try, and agree with those that suggested handloading.
Bob


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