What you see when you look through a riflescope is a superimposition of the scope's reticle, overlaying the image of your target - what you're looking or aiming at.

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The discussion about riflescopes and reticles below is as basic, yet as factual as can be achieved without spending hours in a classroom or at the firing range or both.

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A riflescope - what we see when looking at a physical scope - is comprised of an objective lens (front) housed in the objective bell, an ocular lens (back) housed in the ocular bell, an elevation adjustment turret (top), a windage adjustment turret (right), possibly a parallax correction wheel (left). Eye relief, reticle focus and zoom adjustments are usually found on the ocular bell. On higher end riflescopes, the parallax adjustment wheel may include reticle illumination.

 

​​Riflescopes can have a zoom ratio of, let's say, 4 - 16... meaning, you're able to zoom from 4X to 16X normal view. The objective lens size could be 40mm, 50mm or 60mm. The scope's tube - used for mounting the scope to the rifle - could be a 30mm, 40mm or 43mm diameter tube. Interestingly, the wider the tube's diameter, the brighter the overall image created at the reticle by the objective lens.

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The reticle (see picture above) is a mechanical component of a riflescope. It is adjusted by rotating the elevation and windage turrets.  Adjusting the elevation and windage turrets allow you to set your POA (point of aim) to coincide with the bullet's POI (point of impact).

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You can buy a scope offering a reticle which is positioned in the FFP (First Focal Plane) or in the SFP (Second Focal Plane). You see changes in magnification (along the focal plane) when you adjust the ZOOM range. On a FFP scope, the reticle grows or shrinks along with the visible target size according to how you turn the zoom knob. On an SFP scope, the reticle remains the same size regardless of the zoom setting. Only the target size grows or shrinks in a SFP scope.

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In the reticle image above, we see a vertical (elevation) reference line and a horizontal (windage) reference line. Along each of these reference lines you see subtensions. Subtensions are similar to graduations you see on a ruler or tape measure. Below the windage reference line you see a series of horizontal dots. These dots may actually provide a different or separate set of features from the windage or elevation subtensions. But, they do have a similar pattern as the elevation and windage subtensions. The riflescope's User Manual will explain how to utilize the subtensions, including the ones below the windage reference line. Some reticle designs may allow you to 'range' a target to calculate or estimate the target's actual height and width. You might be able calculate or estimate the 'lead' on a lateral moving target. In other words, "if I aim here - ahead of the moving target - the bullet will impact the target by the time the target gets to my point of aim".  Really cool stuff.

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Riflescopes are also manufactured in accordance with measurement scales. So, you may see a MIL scope or a MOA scope.  MIL refers to milliradian - a metric measurement. MOA refers to minute of angle - an imperial measurement.

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In reality, using a riflescope to achieve accuracy or precision in long range shooting requires the shooter to visualize a FLAT plane (the image seen), include DISTANCE (a linear value) and end up with an ANGULAR solution.  How cool.

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MOA - Minute Of Angle - refers to 1/60th of a degree. Based on 360 degrees in a circle.

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A MOA translates to a 1.047" circle at 100 yds. If you project that cone out to 200yds, a MOA is 2.049" circle. Further projection out to 300yds, a MOA is 3.141" circle and so on.

 

For simplicity, the fractional part of these values are disregarded giving us an easier to remember relationship between distance and an angular spread.  So, 100yds = 1 MOA, 200yds = 2 MOA, 300yds = 3 MOA and so on. MIL and MOA measurements are specific to the particular scope and are not interchangeable.

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Riflescope measurements are angular measurements, DO NOT CONFUSE scope measurements with distance measurements.

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​CAN WE ZERO PLEASE

So, you've just had your riflescope mounted to your rifle. Before you fire the first round, you can reduce your ammunition waste at the range by 'bore sighting' your rifle. Let's get some basic measurements. You need to determine how high your riflescope is above the barrel. This is referred to a height over bore. Locate the split in the mounting rings where the upper and lower sections get screwed together. This is the midpoint along the scope's tube. Next, determine the midpoint of the barrel. Now, measure the distance between the scope's midpoint and the barrel's midpoint. That measurement is the height over bore. You'll need this value later when you begin to use digital firing solutions to get accuracy out of your rifle. You'll be able to build DOPE for your rifle and ammunition. Recall, DOPE was mentioned in Long Range Shooting.​

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If your rifle is a bolt action rifle? Remove the bolt. If your rifle is an MSR, separate the upper from the lower, remove the charging handle and the bolt. Support the rifle or barreled upper firmly. Unscrew and remove the scope's elevation and windage caps exposing the turret wheels. If you don't have protective caps, you'll be using the actual turret wheels. Point the barrel at an object. Pick an object that's about 100yds or further. Look down the barrel from the chamber end through to the muzzle end and steady the platform when you see a distinct reference point on whatever you're pointing at.

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NOTE: What you're trying to see when you look down the barrel is (conceptually) a donut within a bigger donut.  The bigger donut is the chamber donut and the smaller donut is the muzzle donut.

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Follow these two steps. Keep the barrel absolutely rocksteady. Rotate the elevation turret UP or DOWN until the reticle's horizontal reference line is vertically in line with the aiming point. Next, rotate the windage turret LEFT or RIGHT until the reticle's vertical reference line is horizontally in line with with the aiming point. Congratulations. You've just bore sighted your rifle.

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Remember, the further away the reference target is from your bore sighting position, the more reliable the bore sighting results will be.  All you're doing here is building confidence you'll be on target when you go live at the range.  You won't be hunting for off-target hits in the dirt or bushes next to your target stand. Your impacts should be on-target.  They may not be dead center yet.  See the HINT below...

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THAT WAS EASY

You're now hitting 1" bottle caps from the short end of a football field to the other end - 100yds.  What changes when someone adds four more football fields together. That's 500yds. Can your scope dial in a 500yd zero?  What if the target was 1,000yds away or further? Can your reticle dial in 1,000yds or further?  Did you run out of MOA?  Where - within your reticle - did the well run dry?  What is the MAX elevation and windage specs of your reticle. Can you have too much? Can you get more?  Within the scope's total available elevation and windage adjustments, what percentage of either is reliable?

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​HINT

So, you're all bore sighted by the time you get to the range.  Your first shot on target (POI), is not where your POA is. No worries. A quick fix is - without adjusting either turret, get the rifle and the scope's POA back to the exact position BEFORE you took the first shot.  Hold the rifle rocksteady.  Without someone to help you, it could be challenging to make this adjustment. Reach up to the turrets and turn the Elevation and/or the Windage Turret until the reticle crosshairs move to the POI of the first shot. Reposition the rifle such that the crosshairs are again on your original POA. Fire the next shot. Your next shot should impact your original POA.  In other words, you moved your reticle's POA to match the previous shot POI - all while holding the rifle rocksteady. Done correctly, your POA and POI are now in sync.  You may have to make smaller adjustment to correct for any misalignment.

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Do not fall into a rabbit hole chasing POI each and every shot.  If the rifle and/or the ammunition is new or your shooting skill is in learning mode, you can easily be tempted to re-adjust the turrets each time POA and POI do not coincide. ​​​

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DIGITAL SOLUTION

Looking up a Firing Solution for the 300WM pushing a 180gr TTSX. and zeroed at 200yd

 

POI =  1.5" HIGH at 100yds.  Remember "height over bore"?

POI =    7" LOW at 300yds.

POI =  41" LOW at 500yds.

POI = 164" LOW at 800yds.

POI = 315" LOW at 1,000yds.

 

A 1,000 yard attempt requires 120 clicks of elevation.  The concern would be... even if I had 120 available clicks, how many of the top-end clicks are accurate and reliable, and, getting out to 1,000yds... 315" LOW.  Dialing in 315" of elevation for a 1,000yd shot means the scope MUST offer 30MOA or 120 clicks.​

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A HAPPY PLACE

This above section may seem a bit out of context. However, for load development testing, below, we're going to raise the reticle UP by 1 MOA. This moves the point of impact (POI) UP by 1 MOA so it is easier to see the impacts on a clean white area  - a 1" square white box above the point of aim (POA) of the target. The photo below shows a target used for confirming powder charge (the load) and how the projectile performs with that load. You can also use the same type of target to confirm the effects of adjusting the projectile's seating depth or cartridge overall length (COAL).

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First, we prepared 25 rounds, creating 5 five-round groups where each group had a specific incremental load. Remember, the rifle is zeroed for 100 yds.​​​

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Day #1: Each group of 5 rounds was fired at the respective black dot within the orange diamond - our POA. Examining each of the five group impacts, we determine which white square above the orange diamond showed the tightest group hits. Using the load for the tightest group, we loaded up another test group. This time, 15 rounds - also in groups of five - giving 3 five-round groups. Now, we reduce the load of the best group of 5 rounds by 2%, kept that exact load for the middle group of 5 (above), and increased the load for the 3rd group by 3%.

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Day #2:  We essentially 'rinsed and repeated' Day #1. The target results showed a very tight hit consistency between the middle group and the +3% group. Initial conclusion? We've found a good load for this projectile.

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If you've ever seen a slow motion video of a projectile leaving the muzzle of a barrel, you'd see a flexing or whipping motion of the barrel as the projectile is forced, under extreme pressure, out of the muzzle. Visualize a 'sine wave' showing low dips, a median or zero base line and high peaks. Getting the projectile to exit the muzzle at the median or zero line, is the ultimate goal as it results in accuracy. This is typically referred to as a NODE or Harmonic Node.

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We're not done yet. We have the ability to fine tune the ammunition for even better accuracy.  So, we assemble another 15 rounds using the middle load  - from day #2 testing  - plus a +2% load increase. Next, the seating depth or COAL is adjusted. We're talking about really small adjustments - 'thousandths of an inch'. So, five rounds at our starting COAL. The next five rounds were seated 20 thousandths of an inch deeper. The 3rd group is seated 30 thousandths of an inch deeper.

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Day #3: What do we have here?  All 15 POI, when measured, WILL fit within the respective square box - they're all 1 MOA @ 100yds accurate. Target #1 - with 2 shots in the same hole - can fit into the square. Target #2 shows a placement of four shots in an almost cloverleaf with the fifth shot (a flyer) at 2 o'clock - this group of 5 shots can also fit in the square or 1 MOA.  Target #3 is a bit spread out... but, can also fit within the square box.

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Target #2' shows the HAPPY PLACE for this projectile, load and THIS PARTICULAR rifle barrel. The white square 1" box is divided into four 1/2" squares. If we disregard the flyer, target #2 (cloverleaf) is a SUB-MOA of accuracy. Accuracy is usually referred to as MOA - within an 1", or, SUB-MOA - within a 1/2".  The standard deviation SD and extreme spread ES for this project's 3 days of range time are in single digits... meaning there's very little difference in the speed of the projectiles as they travel 100yds.

 

NOTE: Observe the shift in POI for each group in the target below. Target #1, the shift is UP and slightly RIGHT. Target #2, there is ZERO shift. Target #3, the shift is RIGHT and the vertical SPREAD is wider than Target #1. One can conclude we've found a LOAD and a COAL that exploits the HARMONIC NODE of our rifle barrel. Let's not forget, if environmental factors change, this setup could fail in accuracy.

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​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​DISCLAIMER!

The pictures above show a typical riflescope reticle. The design may be unique to the brand of riflescope. It could be showing a MIL or a MOA scale. The majority of riflescopes provide some type of basic functionalities. The scope's User Manual is absolutely necessary for learning how to use the scope's features. Whether you're a weekend warrior, competitive rifle shooter or a hunter, your responsibility is to master the features of your riflescope. A lot of riflescopes present a busy picture. If you're not on top of your scope's A-game and then add a trotting Elk at 325yds or a downrange 600yd wind vane suddenly stretch out and change direction you're in a challenging place. Don't do it.

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Each and every rifle barrel is unique. Like fingerprints, they're all different. Within the same caliber, different barrels can, and will perform with differences, Get to know what your rifle (and barrel) is capable of shooting. The accuracy results shown in target image above is the result of many weeks of finding out which projectile, powder load and cartridge overall length worked efficiently and accurately. If the atmospheric conditions change? So, too, will performance of your ammunition.​

 

We accept no responsibility and/or liability for any adverse results incurred by you for (your) failing to understand you are responsible for your choices and decisions.  Guns, in general, are dangerous! Your failure to use any gun and ammunition in a safe manner remains your responsibility along with any consequences of your abuse!