Need advise...what are the implications of purchasing a double that is regualated at 50 yards without a scope and then installing a scope. Will I have accuracy issues?

I have installed scopes on 2 double rifles, a 9,3x74R Chapuis and a 450/400 3 1/4' British Double.

The regulation with the iron sights was not changed, and the doubles regulated perfectly with the same loads with the scopes mounted.

In short no problems.

Every double 40 cal and under should be scoped, Quick detach mounts of course.

Tell us about your double.

The regulator at HEYM explained it to me as follow: As a rule of thumb, the addition of a scope typically moves the shots farther apart.

So if the rifle was regulated without a scope, the addition of a scope should move the shots apart.

If the rifle was regulated with the scope, the removal of the scope will move the shots closer together.

Again, this is not a 100% rule, but rather the general findings from practical experience.

I think THEORY would suggest that IF your rifle is perfactly regulated at 50 yds with iron sights, adding a scope (with it's additional mass) would have the the recoil up and to the outside for respective barrels taking a bit longer. This would leave bullet impacts slightly lower and possibly not yet crossed, or not crossed as far, as your regulated performance with iron sights. Adjusting the velocity of your loads slightly downward for the scope should give similar performance to your iron sights.

FACT is, in my case with off-hand shooting, I cannot tell the difference at 50 yds between iron sights and a claw mount 1.5x5 scope on my 450/400 3", and I would not think of varying the loads. I am much more confident with my scope at 100 yds...

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Originally posted by AndreC:
...what are the implications of purchasing a double that is regulated at 50 yards without a scope and then installing a scope.

See below.

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Will I have accuracy issues.

Often, there isn't a material difference, but sometimes there is, and there's no predicting which it will be.

Chances are you'll get lucky, and it will shoot fine with the scope. If it doesn't, you'll have to decide which way you'll use it the most. The simple answer is to re-regulate it with the scope. Personally, I wouldn't scope one unless I intended to use it almost exclusively as a scoped rifle - which, in my view, isn't what a double rifle is for. I disagree with my friend Tony, I would consider scoping a 9.3 or .375, but never .400 and up.

quote:

Originally posted by Emory:
I think THEORY would suggest that IF your rifle is perfactly regulated at 50 yds with iron sights, adding a scope (with it's additional mass) would have the the recoil up and to the outside for respective barrels taking a bit longer. This would leave bullet impacts slightly lower and possibly not yet crossed, or not crossed as far, as your regulated performance with iron sights.

No, the reverse is true. If the addition of the scope makes a noticeable difference on a gun originally regulated for irons...since barrel time with a given load is constant, and since the added weight of the scope and mounts dampens recoil, there is less movement of the barrels through the recoil arc during barrel time, resulting in the barrels shooting across, not apart.

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Adjusting the velocity of your loads slightly downward for the scope should give similar performance to your iron sights.

Correct. Reducing velocity increases barrel time, allowing the barrels to move farther through the recoil arc while the bullet is still traversing the bore, which would tend to uncross the respective points of impact. I've seen instances where only going to a heavier bullet or re-regulating would suffice.

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FACT is, in my case with off-hand shooting, I cannot tell the difference at 50 yds between iron sights and a claw mount 1.5x5 scope on my 450/400 3"

It works that way sometimes. Sometimes it doesn't.
-----------------------------------------------
"Serious rifles have two barrels, everything else just burns gunpowder."

I think I was saying the same thing - just not as clearly. see below?

"...adding a scope (with it's additional mass) would have the the recoil up and to the outside for respective barrels taking a bit longer.This would leave bullet impacts slightly lower and possibly not yet crossed, or not crossed as far, as your regulated performance with iron sights."

"...and since the added weight of the scope and mounts dampens recoil, there is less movement of the barrels through the recoil arc during barrel time, resulting in the barrels shooting across,..."

i added scopes to a couple of different doubles, and it made no difference in either. I have to agree that i would much rather not have my 470 scoped, but unfortunately my eyes did not agree, there comes along an age where you just plain can't pick up the sights and then a scope in your answer

Hey folks thanks for all the good insight

quote:

Originally posted by Emory:
I think I was saying the same thing - just not as clearly. see below?

"...adding a scope (with it's additional mass) would have the the recoil up and to the outside for respective barrels taking a bit longer.This would leave bullet impacts slightly lower and possibly not yet crossed, or not crossed as far, as your regulated performance with iron sights."

Emory, the barrels start out crossed, and low, and shoot wider,(un-crossed) and higher as they exit the muzzles. There fore if the barrels are heavier, they will not rise enough and will shoot LOW, and CROSSED, not high and wide!

As you increase weight,the lower, and more crossed the barrels will shoot, if the barrel set's weight is decreased with the same load, the rifle will shoot high, and wide! The weight, and the hight of the scope will also effect the regulation, because of the extra leverage of the high scope's torque on the flip!

So the key is to use the lightest scope you can find, and mount it as low as possible, to avoid as much torque as is possible!

I hope that is at least as clear as Mississippi mud! these things are hard to explain in writing, at least for me!

Mac,

OK, I see why the confusion... If I had more properly said "un-crossed", we would all probably be on the same page.

I do understand the paths start out crossed - if they then "cross", they are un-crossed (in my mind at least when I posted the response). Probably better not carry this part of the discussion too much further or we might be trying to define "is".

I certainly agree with a light and low scope. The center of my scope is about 3/4" above the bottom of the notch of the iron sight V. The scope is zeroed for 100yds and fortunately also produces groups real close to those with the irons at 50 yds. The bullet arcs coupled with the higher scope sight line seem to
compensate pretty nicely.

Thanks

I had my 450/400 for several years before I scoped it.

BIG MISTAKE. I should have had it scoped the day I bought it.

However it was not till a couple years later that I got a 9,3x74R and scoped it, that I learned just how great a hunting gun a scoped double is.

Anything I can do with a scoped 375 H&H I can do, and have done, with my scoped 9,3 double.

Like wise anything I can do with a scoped 404/416 bolt rifle, I can, and have, done with my scoped 450/400 double.

I can make hits on animals with a scope on the double that I cannot make, or would try with iron sights.

Pop it on when you need it, take it off when you don't.

If you have difficulty seeing iron sights and have a double in the 450 and up class, or a bolt rifle, take a look at the Doctor Optic red dot sight.

Tony,

I know you shoot a lot. Have you shot that Big Bore double with the Doctor sight enough to feel confident that the Doctor can take the repeated punishment. I saw Mr.Heath's comment where the one he was using couldn't hack it (it wasn't a Doctor, I can't remember the brand).

Butch

I do not have a Docter Optic on a double yet. I have one on a Blaser 375 Tracker and a Blaser 308 Tracker, and I have shot one on an AR 15.

I do not have enough rounds through one to say if they will take the recoil, but I do know they have been mounted on the slide of a 45 ACP semi-auto [and others], and I have never heard of any problems.

The Blaser 375 H&H Tracker is fairly light and is a pretty good kicker, so far so good.

I cannot remember what red dot Don Heath was using, but I do not think it was a Docter Optic.

Thanks Tony

I remember now----it was a Burris.

I have heard you can expect regulation changes. But I bought a J.P. Sauer 8mm SXS thqt had claw mount bases on it, scope & rings long gone. After thoroughly testing it and developing a good load for it, I had rings made by Paul Jaeger, Inc., & put a Leupold 1X-4X on it. No change in regulation OR point of impact at all......

You won't have any problems, all you have to do is sight it in like any other rifle but with the regulation load...Regulation has nothing to do with sighting in or bringing a gun to zero, once its regulated you can put about any sight on it..