The Quigley Shooting Asssociation
VERNIER SIGHTS.
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Most newcomers to Quigley style shooting will want to fit Vernier type adjustable sights to their rifle of choice. Fortunately there is a fair selection to choose from out there, however, for the most part this may involve importing from America or Europe. Whilst high quality products command high prices, the more economical or lesser priced sights from Pedersoli, Uberti or Armi Sport are more than adequate for the job if you purchase the right one. Here in the United Kingdom, Henry Krank in Pudsey can supply the full range of Pedersoli tang sights.
Most rifle tangs are already tapped to suit, so fitting them is relatively easy, it is when it comes to using them that some shooters encounter problems.
Many are already familiar with modern Vernier target sights and how to read them, but what of traditional long range Vernier sights?
All Verniers work in the same way, with a fixed and a moving scale. Modern Vernier sights made for target rifles are graduated in minutes of angle (60 minutes per degree) each minute subtending approximately one inch at 100yds, two inches at 200yds etc. whereas original and most reproductions are graduated in 1/100ths of an inch or multiples of 1/100ths.
So how do they compare?
It’s been some time since I was at school but I decided to try some elementary mathematics using the following equation;
Tangent of an angle = Opposite side
Adjacent side
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In the diagram, line AB represents the sight radius, line AC the elevation on the rear sight and line BC the barrel line. The angle of elevation is represented by “b”.
The sight radius was measured on my rifle at 34¼ in.
Assuming an elevation of one degree, the tangent of one degree = 0. 017455
Using the equation AC = Tan b
AB
It follows that: AC = 0.017455 x 34.25
= 0.59783375 inches.
So an elevation of 0.598 inches gives an angle of one degree, therefore, as there are 60 minutes in one degree then 0.598 would give one minute of angle.
60
0.598 = 0.009966
60
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Suddenly something is beginning to click.
0.0099 is VERY CLOSE to one hundredth of an inch. Actually, a sight radius of 34.37 inches would make one hundredth of an inch equal to one minute of angle. So for our purpose, we can assume that one hundredth of an inch on our Vernier rear sight will give one minute of angle.
Those “Good old boys” were pretty smart! Especially when you consider that these sights were fitted to muzzle-loading rifles long before the advent of the self-contained cartridge!
On my sight, the fixed scale is marked in inches subdivided into 20ths; therefore each division represents 5/100ths or 5 minutes of angle. What this means to the impact of a bullet at various ranges is dependent on many factors such as muzzle velocity, bullet shape, weight and ballistic coefficient. It is worth noting that on rifles with shorter barrels and therefore a shorter sight radius, one minute of angle on the sight will move the impact of the bullet on the target slightly more but not enough to make a substantial difference.
By now, feeling quite smug and with my curiosity aroused, I decided to compare some of my own data with that found in the excellent little tome called “The Gun that shaped America’s destiny” by Martin Rywell. In this volume, an elevation of 151 points (151/100) is required at 1000yd for a .44in 500-grain bullet ahead of 90 grains of black powder. On my Pedersoli Sharps, fitted with their own Mid-Range Soule sight, assuming that 0 (zero) on the vertical scale represents a line through the foresight parallel to the barrel, then at 1000yds an elevation of only 161 points (minutes) is required to put rounds on the target. (This, incidentally, gives an elevation of around 2 degrees 41 minutes) for a .45in 500grain bullet in front of 65 grains of Swiss number 4.
As I stated earlier, it is a while since my schooling, and so if my theories don’t hold water then feel free to show me the error of my ways.
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Comments and questions please to khall6548@aol.com
