DISCLAMIER: I am not an optics professional. This is merely my opinion so take it for what it is worth.
What I am trying to do in this post is attempt to help the reader have a better understanding of tactical scopes and show how using the reticle and turret adjustments in conjunction with one another will make you a more capable shooter. I will attempt to start off very basic and get more technical as the article progresses. I personally lean more towards the tactical crowd and I prefer MIL reticles but the very same principles apply to MOA reticles and adjustments. The only thing that will change would be the math formulas for ranging. I am writing this with scopes in mind that have the ability of external adjustments and are variable power.
Now let’s start off simple. Scopes are usually listed in three numbers for variable power scopes such as 3-15x50. The first number is the minimum power of the scope. What you see in the scope will be under 3 times magnification or 3x at the minimum power or zoom setting. The second number is the maximum zoom the scope has. In this example 15x or the target will appear 15 times closer in the scope than to the human eye. And the third number is how large the objective diameter is in millimeters, in this case 50mm. The objective is the lens that would be further towards the muzzle of the gun. The lens closer to the shooter or the lens you look through is called the ocular lens. Now there are several other combinations such as 3-10x40, 5.5-22x50, 5-25x56 ect.
Now what does this all mean and what matters to you is all subjective to what you are trying to accomplish. This article is not intended to help you choose scope A versus B so I am not going to get into this is better than that debate. What I am trying to do is make you realize that being able to hit targets at further distances is dependent upon having a sighting system that you can actually adjust or correct to make hits on targets at further distances. With modern rifles and ammo I can take your *deer* rifle and make kill zone hits with it at 500 yards with YOUR gun and YOUR ammo but probably not with your scope. If you spend hundreds or thousands of dollars a year on hunting or shooting sports, invest some money in a better optic that can be externally adjusted, then learn how to use it and you have more success being able to make longer shots accurately.
Here are some points that I look for when selecting optics.
Personally I like variable power scopes with a lot of magnification. I feel if I don’t need the extra power I can dial the zoom back. Don’t get too caught up in magnification because in the hot summers the mirage gets so bad that you cannot dial scopes to extremely high magnifications when shooting 300 yards plus anyway. The magnification amplifies the mirage and the mirage obscures the targets but I still like to have it if I need it. Personally about 15x or so on the top end is my minimum and I have some scopes with 25x ability. It helps out at the range for me to see my bullet holes and not have to go down range to check the target every few shots. If I am hunting or shooting a stage with multiple targets I do not have the magnification dialed very high. The reason being leads me to my next point.
Field of View or FOV
FOV represents how much you are going to see of a target in the scope side to side and up and down. Naturally as you zoom in you are going to magnify the target and make it bigger. But this also decreases your FOV. It is like you are looking through a straw and the more you zoom the worse it gets.
I will try to explain and keep it really basic. Let’s say you have a 4’ long 2* diameter wrapping paper roll and you are looking at an object (say a truck) that is 20’ away. Then you have a 4’ long 24* diameter cement culvert that is 20’ away from the same truck naturally you are going to see more truck looking through the culvert. That is because you have more FOV through the culvert. It is the same thing with scopes. FOV is important for target acquisition. If you are in a competition setting such as a tactical rifle match or even out hunting once you see that target with your naked eyes you want to acquire that same target in your scope quickly. But you want to be able to do it with reasonable magnification on the scope as well.
How much you are going to need is going to be dependent on how far you are trying to shoot. Also some scopes have more elevation adjustment per turn than others. This is important so you do not get lost as to where you are on the turret if your scope is not equipped with a zero stop feature. A zero stop feature will allow you to set a point to which the elevation knob cannot go past. Usually this is set at or near your rifles zero. I zero my rifles at 100 yards. So if I dial the elevation all the way back until it stops I know 0 is for 100 yards. If your scope does not have this feature and you had to dial say 3 complete turns to make a long shot then after the shot you start cranking back down to your 100 yard zero but get lost and ask yourself was that 2 or 3 turns………well now you are in a bind with no way to tell until that next shot.
You need to know this so you can select the correct size rings to mount the scope to a base or rail. Second and possibly most important is tube size plays a big part in the limiting factor for the range of adjustment the scope will have for both windage and elevation. The old standard used to be 1* tubes. Most manufactures are now using 30mm tubes as the standard and some even larger such as 34mm and 35mm tubes. You have to realize that when you make an adjustment to a turret, either the elevation or windage turret, that the erector tube which holds the reticle in the scope is physically moving inside of the tube. The larger the tube body is then the more the erector tube (internal tube of a scope) can move before it hits the tube body and you run out of adjustment. For most hunters sighting in a scope for 100 or 200 yards with no intention of dialing in corrections for longer shots then the internal range of adjustment is not really a concern. Any scope should zero at those ranges without any concern of running out of adjustment. Where this really comes into play is for long range shooting.
For example say the scope you bought has 100 MOA of elevation adjustment. That number is the total range of elevation travel. Most scopes come from the manufacturer with the reticle centered so you would have 50 MOA of up and 50 MOA of down. Let’s assume you put the scope on your gun and you did not have to touch a thing. It was hitting bull’s eyes at 100 yards when you bolted it on the gun. Now you want to shoot at a target that was far enough away it calls for 60 MOA up elevation to compensate for bullet drop from your 100 yard zero. In this example you would *run out of adjustment* because you only have 50 MOA up. One way to compensate for this without buying another scope with more internal adjustment would be to add a base that has MOA built into it. What this does is it tilt or cant the optic on the rifle downward which *adds* elevation travel to the scope. It *takes* the elevation from the downward adjustment and adds it to the upward adjustment. So as in the previous example if you put a 20 MOA rail (the common rail put on tactical rifles chambered in .308 Win and the like) you would have to dial 20 MOA down on your scope to zero at 100 yards. So now you would have 30 MOA of downward travel and 70 MOA of upward travel. So now you would be able to dial that 60 MOA needed to hit the target.
Tracking is the most important factor when dialing in adjustments for long range shooting. If you have a quality rifle with consistent ammunition then you should get very consistent velocity and accuracy. Using a ballistics calculator or spending time at the range learning your gun / ammo combination will determine how much the bullet will drop as the range to target increases. Once you have determined how much the bullet is going to drop for each range that value can easily be recorded in MIL or MOA of correction to dial on to the scope. Write it down and that is your DOPE for that distance. However, if what you dial on the scope is not what the optic gives you then everything else does not matter. If you dial 10 MILs then correction applied in the optic better be 10 MIL’s. Scopes that do not track the same every time are useless for long range shooting.
For instance at the LRA match we had one stage at 1000 yards. A legit KD or Know Distance 1000 yards, not a camp story of I shot that deer at 1000 yards. My DOPE or correction was 10.6 MILs of elevation or to put it another way almost 32 feet of correction (from a 100 yard zero) and I had 1 MIL or 3 feet of wind correction on the scope to account for the left to right wind. When you dial 10.6 it better be 10.6 not close or you WILL MISS. I am sorry but you are not going to do that with a $200 scope.
Light Gathering Ability
There are a few ways to gather more light. The physical limitations are the objective lens diameter and tube diameter. The larger they are the more light they can acquire. But really it comes down to glass and coatings. The better the glass and the coatings are the more light they transmit. The better coatings filter out the *bad* UV light and allows more of the *good* light to pass. This is going to largely depend on how good the glass is and what kind of coatings the manufacture uses on their optics. This is one of the big areas where you get what you pay for. The question you really need to ask yourself is do you need it? That is subjective to each person for the intended use of the optic.
This is simply the distance from the ocular lens to your eyeball. This is a major concern with larger caliber rifles. You want to have a big enough of a gap between your eye and the scope so when the gun recoils you do not injure yourself by the scope coming back and hitting you in the face. There have been some really nasty cuts requiring ER visits and stitches by not having proper eye relief. The end of the ocular tube is usually very sharp and can cut.
Most tactical style scopes have an adjustment for parallax. A common misconception is that the parallax adjustment is a *focusing* knob. While it may indeed bring the image in and out of focus this IS NOT WHAT THIS IS USED FOR! It is to bring the plane of the image inside the scope into the same plane as the reticle. What happens is as the distance to the target changes the image moves out of the same plane as the reticle. When this occurs if you move your head side to side, or up and down, without moving the gun, the reticle will move or *floats* on the target. THIS IS BAD and it will cause your shots to be off and your group size to increase. Matter of fact in lower end scopes when the parallax is set properly the target may not be in the best focus.
Think of it like this, if I tell you to stick a target on a wall then I give you a cross on a stand (crosshairs) and tell you to stand 10 feet from the wall but put the cross 5 feet from the wall in perfect alignment with the bull’s-eye of the target. The cross hairs will only cover up the bull’s-eye of the target if your eye is in perfect alignment with the cross (crosshairs). If you move your head side to side or up and down the crosshairs will move on the target because the crosshairs and your eye will no longer be in alignment with the bull’s-eye. However, if I tell you move the cross to the wall (adjust the parallax) so that the cross (crosshairs) is in the same plane as the target (ie against the wall) then you can be standing / sitting / move your head up or down, left or right and no matter what the cross covers up the bull’s-eye of the target. That is parallax!
In my example we moved the reticle which is technically opposite of what actually happens (the image moves to the reticle not the reticle to the image) but the example explains the principle. When the parallax is set properly moving your head will not affect the reticle on the target, it will stay stationary. To check to see if you are parallax free; with the gun supported front and rear by sand bags or a combination or a bipod and rear bag; without moving the gun, move your head very slightly up and down or side to side and see if the reticle moves or floats on the target. If it does then the scope is not parallax free. You need to adjust the parallax knob until there is no *floating* of the reticle on the target. It takes some practice to be able to move your head slightly without moving the rifle but once you get the hang of it and see parallax it will explain why your zero has moved on you in the past. Meaning *man last time I was at the range it was dead on, now I am high*. You cannot be this steady if you are trying to free hand the rifle or do not have a good rest. To see the effects of parallax for yourself set the parallax to say 100 yards then focus on a target that is 300 yards away and move your head without moving the rifle. The cross hairs will float all over that target without the rifle moving. That is how much error is in your shot if you do everything else perfect! You need to adjust the parallax out of the scope before making the shot to remove this inherent error.
With Premier and S&B optics when the parallax is not set properly at closer ranges (within 300 yards or so) the image of the target is blurry and you will naturally adjust it to bring the image into focus and hence correct for the parallax error. However I have noticed that with NightForce scopes the image remains in focus at almost all parallax settings. A friend and I were trying to sight in his gun with a NightForce optic and we were getting groups over an inch with the groups from string to string shifting point of impact. One group would be high then the next would be right ect. Finally we checked for parallax and the reticle was moving about 2" on the target. This has been the cause of MANY missed shots and wandering zeros.
I do not know of a true quantifiable number or measurement of this but the following is what it refers to. When you shoulder your gun assuming everything is properly set up then you should get a clear sight picture without having to try to "find" the target. The image in the scope should be clear from the very edge of one side to the other both up/down, left/right and should not have any blackness or darkening to it. This will depend on having the cheek piece of the stock at the proper level for the height of the rings and the scope being the correct distance from your eye so that you do not have to lean towards the scope or away from it to have a full sight picture.
What "eye box" represents is how much you can move your head left/right or up/down and not lose the image in the scope. Some scopes have a very narrow eye box and just slightly moving your head will result in you losing the image. Now this is not to be confused with the stock and optic not being set up for the shooter. Example, if you go with higher rings then you would need a higher cheek weld. To achieve this you may need to add height to your stock by way of a stock pack or even say a mouse pad or some foam and tape. (It may not be pretty but it works). Or if you have to lean forward a bit to get a clear image then this tells you the scope is too far away from your eye and you need to move the scope back some or shorten the length of pull (distance from the rear pad to the trigger) by cutting the stock or removing spacers that some stocks are equipped with.
Now there are other aspects of scopes that may be a consideration as well but I think I hit the high points.
MIL vs. MOA Reticles
Now I will get into the meat of the topic. Everything you have read to this point is considerations when buying an optic. Now we are going to learn how to use tactical reticles.
If you decide that you want to become a better shooter and want to be able to hit targets further out then you need to know how to correct for it and not just guess by aiming high. The first barrier you are going to have to overcome is you have to be open to the idea of external dials for adjustment. I think most guys with hunting back grounds shy away from that because they just do not know how to use them so it is a turn off. They have been taught just sight it in a little high at 100 yards and if the target is past 200 yards then aim high. Well your aim is a guess unless you have something in the reticle to use like a "grid" (MIL or MOA) or BDC (Ballistic Drop Compensated reticle). And you know how far away the target actually is.
The thing I like about the "grid" reticles such as the MIL based or MOA based is that they will work for any gun shooting any caliber or bullet. You just have to figure out where on that grid you are going to hit with your particular bullet / velocity combo. This is very easy with a ballistics program or just going out to the range and shooting at varying distances.
The last and most important choice to get 100% out of your scope is the reticle and understanding how you use the turret adjustments IN CONJUNCTION WITH the reticle. MATCH THE TURRET ADJUSTMENTS TO THE RETICLE. IF YOU DON’T QUIT READING AS THE FOLLOWING IS POINTLESS.
What I mean by this is if you have a MIL based reticle such as Mil-Dot or any variation such as NightForce’s MLR, Leupold’s TMR, ect then get the MIL turrets (0.1Mrad per click)
If you do not understand or do not want to learn MIL and are comfortable with MOA then that is fine. Get a reticle that is MOA based and get the turret adjustments in MOA (usually 1/4 MOA but some are 1/8, 1/2 or 1 MOA per click). Just make sure they match. Reticle/Turret MIL/MIL or MOA/MOA do not go MIL reticle / MOA turrets.
Ok now what is a MIL and what is a MOA? The whole point of the following is to try to explain and understand how much the bullet is going to move when you dial correction into the scope turrets.
A MIL is a milliradian which is a unit of angular measure. Most people think MIL is metric and MOA is a standard unit and both of those are entirely WRONG. It is just a unit. The reason most people think standard and metric is because of the way the math of the two reticles work out.
1 Minute of Angle is a slice of a circle. There are 360 degrees in a circle. Each degree can be further subdivided into 60 Minutes. 1 Degree = 60 Minutes. So one minute or one MOA is 1/60th of a degree. Now we need to know what kind of a change is this going to make to our impact point.
Think of yourself as standing in the middle of a large pie and you shoot a laser to the rim of the pie that is 1000 yards away. Now walk along that lasered line and every 100 yards put a marker and let’s call that line A. So you have 10 markers on line A. Now come back to the center of the pie and turn your laser 1 MOA and shoot your laser again to the rim of the pie. 1000 yards away. Walk that line and every 100 yards put a marker and let’s call that line B. The two lines would form a *slice* of pie and the angle between those two lines would be 1 MOA or 1 Minute of Angle. Now what we want to know is from the markers on line A to the markers on line B how far apart those two markers are. This is how far the bullet is going to move when you dial adjustment into the scope. 1 MOA will move your point of impact 1.047197580733 inches at 100 yards. Most people just drop the decimal and say 1 MOA will move your point of impact 1* at 100 yards. The 200 yard markers would be 2* apart, the 300 yard markers would be 3* apart, so on and so forth.
Now if your scope is in 1/4 MOA per click adjustments then 1 click is going to move your bullet 0.25* at 100 yards, 0.50* at 200, 0.75* at 300, 1* at 400……If your scope is 1/2 MOA per click then 1 click would move the bullet 0.5* at 100, 1* at 200, 1.5* at 300, 2* at 400 ect.
A MIL is a milliradian. A circle has 2 PI Radians or 6.28 approximately radians. Now forget about that for a minute and let’s go back to our example of standing in the pie but now for MILS instead of MOA.
So now we have shot our line A and now we turn the laser 1 MIL instead of 1 MOA and shoot line B. How far apart are our markers? 1 MIL = 3.6 inches at 100 yards. So at 200 it would be 2 x 3.6* = 7.2* inches, 300 yards 3 x 3.6* = 10.8*, ect. Now the MIL based scopes are in 0.1 MILs per click.
One click is going to move your point of impact 0.36*/100 yards. So you would need 10 clicks to equal 3.6* at 100.
1 MIL = 10cm displacement at 100m. But each click is 0.1 MILs. So if we had done the pie example but went to 1000m and put the markers every 100m instead of yards it would be 1cm per click at 100m, 2cm at 200m 3cm at 300m ect…..
So now that we know 1 MIL = 3.6* at 100 yards and that MIL turrets are 0.1 MIL / click or 0.36*/click at 100 yards.
We also know that 1 MOA = 1* (dropping the decimals) at 100 yards. Most tactical style turrets in MOA are 1/4 MOA so 1 click would be 0.25* at 100 yards.
So MIL turrets that are 0.1 MIL/click are a more coarse adjustment than 1/4 MOA/click turrets. So if you want a finer adjustment this may be a reason to go with MOA instead of MIL.
Ok now that your brain is hurting forget all the numbers and just think simple. I know when I make a click on the scope it is going to make a change to where the bullet impacts. How much is going to depend on if I am using MIL or MOA turrets and if I am using MOA it will further depend on what the turrets are calibrated for, meaning 1/8, 1/4, 1/2, or 1MOA. We all know bullets like all objects on earth fall. How much they fall before they get to the target will depend on the bullet itself and the velocity it left the barrel with. Lucky for us there are some really good ballistic programs that can tell us exactly how much the bullet is going to drop due to gravity and move left / right due to wind. All you need to know is the bullet you are using which will determine the drag characteristics and what velocity the bullet had when it left the gun. I use Ballistic AE which is a $20 app for the iPhone. Having it on a portable device is very convenient to bring with you to the range or to a match.
Again the most important thing is to match the turrets (adjustment knobs) to the same scale that the reticle (grid / ruler) is in. So MIL/MIL or MOA/MOA DON'T MAKE THE MISTAKE and get a MIL reticle / MOA adjustments. Then you have to remember 2 numbers for each distance. So if you have a scope such as a Leupold Mark 4 with a Mil Dot retical (or any scope for that matter) with 1/4 MOA dials it is ass backwards.
Example for a 100 yard zero at 400 yards with my gun/ammo combo I need 2.2 MILS of elevation correction to correct for bullet drop. Which converted to MOA would be 7.5 MOA high. So if I had a MIL/MOA scope then I would have to remember hold over 2.2 Mils if I am not going to dial or dial 7.5 MOA to correct for the drop. Two numbers to remember instead of one.
If the previous example had matched the reticle and turrets then in MOA/MOA then all you need to know is if I have a 100 yard zero and I aim 7.5 MOA high (use the reticle and aim 7.5 MOA up) or just dial 7.5 MOA on your elevation knob and you can hold cross hairs. Same to be said if you prefer MIL based then either hold 2.2 MILs high or dial 2.2 MILs up and hold cross hairs. Now you only have one number to remember or have taped to your stock. It is really easy to make a sticker in excel.
Sighting in and using the reticle for adjustments.
This is the easiest thing in the world to do when you match the reticle and turrets. Ok you are at the range and you shoot your first shot at say 100 yards. You are on the paper but need to adjust. All you have to do is use your reticle to measure how far off you are. Let’s say you are high and right. To determine exactly how much high and right use the reticle to measure. Say the shot was 2 MILs high, you know this because with the cross hairs over the bull’s eye the shot is even with the second line on the vertical axis and 3 MILs right, again the bullet hole is 3 lines to the right. All you have to do is dial 2 MILs down and 3MILs left and all things being equal your next shot is dead center. Trust me it works.
This is the same principle when you miss but see the splash of the round. Say your elevation was good on a shot but you failed to account for the wind and you see the splash was 1MIL right. Run the bolt and hold one Mil Left and your next shot will impact the target if you broke the first shot clean and the wind held steady. Same thing applies with elevation. If you see where the first round went run the bolt and hold where that round impacted. That is the DOPE (Data On Personal Equipment) you need for that target.
Now if you had not matched the reticle and the turrets and say you had a MIL based reticle and MOA turrets (MIL/MOA) now you have to start converting the MILs to MOA. The conversion would be as follows:
MILS x Distance in yards / 100 x 3.6 (because 1 MIL = 3.6inches at 100 yards) = MOA
So the elevation would be 2 x 100/100 x 3.6 = 7.2 inches or approximately 7 1/4 MOA
The Windage would be 3 x 100/100 x 3.6 = 10.8 inches or approximately 10 3/4 MOA
THIS IS THE REASON YOU MATCH THE TURRETS TO THE RETICLE! As you can see the conversions are a PITA. MATCH THE TURRETS TO THE RETICLE then all you have to do is dial the correction you *measure* using the reticle.
Some people like them and they work decent but I do not like the BDC reticles. They are calibrated for a specific bullet going a specific velocity under specific atmospheric conditions. Any variation to that and it is off. In my opinion just buy a MIL or MOA reticle and again just learn the "grid" and where your combo is going to hit. Works on any gun with any caliber not just what they etched into the glass for the specific bullet / velocity / atmosphere combo the BDC reticle was intended for.
First off the best way to range is with a LRF Laser Range Finder. They will be much more accurate than you will but they do have their own limitations. But for the sake of posterity cause batteries die and LRF’s break I will touch on the subject. Ranging with the reticle depends on you knowing the size of the target and coming up with tight measurements of the target in MILs or MOAs. Slight variables in either of these two numbers can throw off the distance to target. The error becomes dramatic the further out the target is and the more you are off.
For MIL reticles the formula is,
(Size of the target in inches x 27.778) / Size of the target in MILs = Range to target in yards.
You are looking through your scope at a 72 inch tall target (6 feet) and the bottom of the target is at the crosshair intersection and the top of the target is at the 2 MIL line in your reticle. Do the math to determine the distance.
72in x 27.778 / 2Mil = 1000 So the target is 1000 yards away.
For MOA the formula is:
Size of target in inches / Size of target in MOA x 95.5 = Range to target in yards.
First Focal Plane or Second Focal Plane?
Lastly you need to decide what plane you want your reticle in, First Focal Plane (FFP) or Second Focal Plane (SFP). All reticles will either be FFP or SFP. If as you adjust the magnification the size of the reticle changes and grows or becomes bigger as you increase the zoom then you have a FFP scope. If as you adjust the magnification of your scope the size of the reticle does not change in size then you have a SFP scope. Now you might be wondering why is this important? The answer is for ranging and using the reticle for holdovers instead of dialing in an elevation correction.
If you have a FFP scope and you need to hold 2 MILs over a target then it does not matter what you have the magnification set on. Because as you increase the zoom on the scope and the target gets larger so does the reticle because the reticle *grows* proportionately with the image. So the reticle stays in calibration at all magnification settings. So the 2 MIL line is actually 2 MIL over the target at any magnification.
If you have a SFP then the reticle is calibrated for a specific magnification. Usually it is the highest power the scope can achieve but some manufactures calibrate to 10x. This becomes very important when ranging or holding over to know what power the reticle is calibrated for.
Example: You have a 5-20x50 scope but the reticle is a SFP and is calibrated for 10x. You need to make a shot that calls for 2 MOA elevation correction and want to hold over. If you are at 10x then you hold 2 MOA over. However, assume the target is further away and you need more magnification and you have the reticle set to 20x then the target is going to seem twice as big so you need to hold over twice as much to compensate for the difference. You would need a 4MOA hold on the reticle.
Same to be said when ranging, if the target is far away and you put the scope on 20x and the target takes up 4 MOA of reticle it really is taking up twice as much as it should because the image is twice as large as what the reticle was calibrated for. So you would have to remember that when doing the ranging calculations and use 2MOA instead of the 4MOA the target is taking up.
That is the reason why I like FFP scopes. Your holdovers are the same no matter what magnification the scope is set to. No chance of getting lost or confused. The only down side to FFP scopes is that some people do not like how small the reticles can be at low power. And FFP scopes are more expensive than SFP.
What sets high end optics apart?
What really sets the higher end scopes apart is the clarity of the image due to the glass and the coatings for longer range as well as low light conditions and the precision and repeatability or tracking of the adjustments for dialing corrections for long range shooting. If glass clarity is not a huge concern and all you want to do is zero the scope and never dial in a correction (tracking becomes mute) then a cheap scope may fair just fine as long as it can hold a zero and the reticle does not drift on its own.
The average person wants to zero a deer rifle at 100 yards and will never shoot past 200. You do not need to break the bank to do that. But trust me the saying *You Get What You Pay For* never holds any truer than when speaking optics. All scope brands break. They are mechanical machines made by man. But there are companies with better historical results than others.