Is there a formula for setting a vernier sight?

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Widows Son

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One of the elder statesman of our gun club was telling me over a pint of homebrew that he used to have a mathematical formula for quickly adjusting the vernier scale on a tang sight. Using the formula, the distance to the target and a pocket calculator he could quickly adjust his sight for elevation and take his shot. (It only worked for elevation).
Alas, years of perfecting his homebrew had caused him to misplaced this formula.

Would such a formula exist or was enjoying his communion with Bacchus Dionysus? ;)
 

Phil Coffins

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I would venture to say that it would be rather complex. The scale on my sight is constant, that is the graduations from bottom to top are evenly spaced. The flight of any given projectile changes as distance increases depending on its speed and the shape of said projectile. This means the arch isn’t constant. There are generalizations that can be made to put you on the target but then altitude and humidity come into play. I wonder if he ment formulas rather then formula.
 

Idaho Ron

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In this video he is increasing by .015 per 100. He knows his rifle and load well.

On my rifle I use .010 per 100 yards. The farthest I have shot so far with that load is 500 yards.
 

dave951

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Short answer- no there is no universal formula. What you have to know is how much you need to move the sights at different distances. This is because of the trajectory differences between rifles/loads. In short, there is no substitute for practice at the distances you intend to shoot. Go to the range.
 
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And the distance between the sights changes the formula as well.

As Dave951 says, go shoot, when your dialed in write down that sight setting, different days it will be slightly different at long range due to little things even humidity, but your settings will get you close enough to fine tune, then write that setting down as well. (a spotter with a good scope is invaluable)
Pretty soon you will have a log book.
 

excess650

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With a 36" sight radius, .010" sight adjustment is very close to 1moa. For a shorter sight radius, the adjustment is less, and longer is more. Once you have a "zero" for a distance, write it down and move to another distance and repeat as necessary. Write all of this down! This data will be pertinent to this rifle with this load.
 

Widows Son

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Thank you for your replies. I suspected the old gentleman was telling a porky, however I thought it worth asking.
 

dave951

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Another way to think of this is the venier is just a set of reference marks that in no way correspond to any set amount of movement at distance. That figure has to be determined by experimentation with your specific rifle and load
 

Khufu

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there is an easy formula, for round balls, use the round ball ballistic calculator, for conicals use the BC and plug that into any ballistics program.
you will need to know the muzzle velocity. you can then calculate MOA drop at any distance and set your sights accordingly. windage can also be calculated, if you know the windspeed. there are smartphone apps to measure wind speed, and ballistic calculator apps. USGS maps can be used to determine range in the field as well as google earth.
 

TFoley

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there is an easy formula, for round balls, use the round ball ballistic calculator, for conicals use the BC and plug that into any ballistics program. you will need to know the muzzle velocity. you can then calculate MOA drop at any distance and set your sights accordingly. windage can also be calculated, if you know the windspeed. there are smartphone apps to measure wind speed, and ballistic calculator apps. USGS maps can be used to determine range in the field as well as google earth.
Yup, just like they did in the good ol' days, eh? ;)
 

dave951

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there is an easy formula, for round balls, use the round ball ballistic calculator, for conicals use the BC and plug that into any ballistics program.
you will need to know the muzzle velocity. you can then calculate MOA drop at any distance and set your sights accordingly. windage can also be calculated, if you know the windspeed. there are smartphone apps to measure wind speed, and ballistic calculator apps. USGS maps can be used to determine range in the field as well as google earth.
Sorry Ghostrider, modern whizbang won't work with venier sights. The venier scale doesn't correspond to moa, rads, or any other system. It's just a scale to measure how far you move the sights. It's up to you and actual range experience to determine how far each gradiation moves your point of impact for your rifle and load at a given distance and you'd best keep good notes.
 

fleener

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Excess650 is on the mark.

With a 36" sight radius on a MVA sight, it is very close to 1 MOA. Also as stated, keep a book for this rifle. I write down the date, location, bullet, wad, powder, starting sight setting and ending sight setting.

I dont get hung up with being perfectly on paper with the first shot. You can shoot at the same range an hour apart and have a completely different sight setting. You just have to be willing to crank on the sight when it is needed. Even in the same match you might go up with the rear sight for a few shots, only to end up working your way back down.

I like the book "The Wind Book for Rife Shooters". The do a good job talking about reading the wind and sight adjustments.

When I first started shooting long range I made up a whole table of sight adjustments based on wind speed and direction of wind based on my load. Wind at 1 o'clock has less value then a full value wind at 3 and 9 o'clock.

Fleener
 

Art Caputo

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Yes, I have found the formulas to work with my 34” Sharps/Montana sight with 1MOA/click. As mentioned above, when converted to MOA with the rifle’s zero established, results will be quite consistent with a specific load. The drop values at chosen distances still need to be determined by actual shooting results. While not period correct, I entered the ballistic information(MV, BC, bullet wt., etc) into my ballistic rangefinder and found with a bit of tuning, I could range, set my vernier sight, and shoot out 10” steel targets to out to any range out to 500+ yards with a high degree of certainty taking both elevation and wind corrections off my Gunwerks G7 Rangefinder. I have used the same approach with my long range(unmentionable) 22 rimfires with similar success.
 

Khufu

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Sorry Ghostrider, modern whizbang won't work with venier sights. The venier scale doesn't correspond to moa, rads, or any other system. It's just a scale to measure how far you move the sights. It's up to you and actual range experience to determine how far each gradiation moves your point of impact for your rifle and load at a given distance and you'd best keep good notes.
actually, it does, measure the distance from the front sight to the rear sight and the heights of the 2 sights. Sin of the angle = opposite over hypotenuse. 1\60 degrees = 1 MOA very easy to calculate how many thousandths 1 MOA is for YOUR individual rifle. calculate a chart of drop every 10 yards, and shoot a few shots at a few different ranges just to verify the chart. I use the same formula to calculate the needed front sight height on C&B revlovers rather than make it tall and grind it down by shooting and grinding method.
 

Khufu

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Yup, just like they did in the good ol' days, eh? ;)
if it makes you feel better, you can hand write the table on some parchment and title it " Ye Olde drop table"
I bet your barrel was not hand forged around a mandrel and I bet your powder is a lot better and more consistent than what was available in the good old days. as much as we love our smoke poles, some "modern" is going to find its way in. as expensive and rare as powder is, why waste it figuring out a drop table when a little math and calculators will save pounds!
 

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