The great thing about a crossbow is that it's consistently accurate even without much training or practice on an archery range. However, to take advantage of this, your crossbow scope must be sighted in correctly. Luckily, this isn't a difficult process if you know what you're doing, which is why we created this step-by-step guide to see through it.
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Different Types of Crossbow Scopes
There are three main types of crossbow scopes:
Red dot scope
Speed dial scope
Not to worry. While all these scopes function a little bit differently, the process of sighting them in is essentially the same. That said, we will be noting some minor differences, so let's go over the basics of each scope first so you know which one you're dealing with.
A "reticle" is basically a crosshair. In other words, a multi-reticle scope is one calibrated for various distances using several crosshairs. Usually there's one large reticle, often representing 20 yards, with two lines running from the sides of the scope and meeting in the center. Beneath the long horizontal line, there are then several more shorter horizontal lines for longer distances.
Red Dot Scopes
Red dot scopes aren't much different from multi-reticle scopes. They just use red dots instead of crosshairs. Oftentimes, this is advantageous because the red dots can be illuminated and are easy to see and target, but they don't obscure too much of your vision through the scope. In some cases, scopes combine both reticles and red dots, usually with a red dot in the center representing the shortest distance, normally 20 yards, and reticles below for the longer distances.
Speed Dial Scopes
Also known as a variable power scope, a speed dial scope is one that can be set specifically to your bolt speed. Since bolt speed can change if you use bolts that weigh differently than those the crossbow was rated for or otherwise change the weight by attaching broadheads or by changing the crossbow's settings, the bolts may not drop in a way that lines up with the reticles. A speed dial scope has an extra dial for adjusting it based on your bolt speed.
Speed dial scopes are standard equipment on fast crossbows.
Parts of a Crossbow Scope
Before learning how to sight in your crossbow scope, you need to know the parts of the scope that you'll have to adjust. These include:
- Reticle: The reticle is the crosshairs that lines up with your target when you look through the scope.
- Lens: The lens is the transparent piece of the scope that faces the target.
- Eyepiece: If you didn't guess, the eyepiece is where you put your eye to look through the scope.
- Elevation adjustment knob: Usually located on the side of the scope, this dial adjusts the scope vertically so that the reticles line up with the target vertically.
- Windage adjustment knob: Usually located on the top of the scope, this dial adjusts the scope horizontally so that the reticle lines up horizontally. In some cases, this allows you to adjust for wind that is throwing the bolt off course.
- Speed dial: On a speed dial scope, this is the dial you turn according to your bolts' fps.
Equipment You Need to Sight in Your Crossbow Scope
Aside from a crossbow, bolts and a scope, we recommend a few more things to make sighting in your crossbow a little easier:
Additionally, things will be a lot easier if you have plenty of extra bolts and practice broadheads because you won't have to keep walking to and from the target to retrieve your bolt and can instead use the field binoculars to see where each shot lands.
Sighting in a Crossbow Scope Step by Step
Step 0: Find Your Bolt Speed and Adjust Accordingly
This step is only necessary if you have a speed dial scope. Your crossbow likely has an advertised bolt speed, but this is based on a specific weight. Using different bolts, changing the weight with broadheads, or changing the speed of your crossbow itself will change this. That can throw off the crossbow scope which will have the reticles positioned to account for the drop based on the rated bolt speed.
Many crossbow manufacturers include a chart in the manual that will provide you with a general guide for bolt speed based on bolt weight. If you want to be as specific as possible, though, go to an archery range that has a chronometer or get your own. A chronometer measures the exact bolt speed, and you can then set the scope's speed dial accordingly. It is one of the bow tuning tools every home archery shop should invest in.
If you don't have a chronograph, you can find the speed of your crossbow bolts by a little trial an error.
Start at the manufacturers speed claim. After you have sighted in at 20 yards, your other aimpoints should be perfect.
If they are not, do the following:
If your bolts are hitting low, adjust the speed higher until they are right on.
If your bolts are hitting high, adjust the lower until they are right on.
Step 1: Set Up Your Target
To sight in your crossbow scope, you have to shoot it repeatedly at a target. We recommend a standard foam target because the flat target surface will provide for more consistent shots than a rounded straw or 3D target.
Set it up in an area with plenty of room, ideally enough room to take shots from the longest distance your scope has a reticle for, probably 70, 80, maybe even 100 yards. Yes, some of the best crossbows are now capable of accurately shooting that far.
Now, use your colored masking tape to put a cross on the front of the target. It helps if you put the intersection of the two pieces of tape higher up on the target's face to account for more drop from longer distances.
The same way that you would for walk back tuning.
Step 2: Adjust the Windage
Now that you have your target set up, use the tape measure to measure out the distance from the target that corresponds with the primary top reticle of your scope, probably 20 yards. If you have a rangefinder, it's also a good idea to check that it's stating the same distance as the tape measure.
Standing at 20 yards (or whatever your scope's minimum distance is), aim with the corresponding reticle at the center of the cross you made on the target. Take a shot using the same bolt you'll use hunting, ideally with a practice broadhead that's shaped the same and weighs the same as the broadheads you'll use in the field.
Naturally, your shot will probably miss the mark both horizontally and vertically, but just worry about the horizontal orientation, or windage, for now. Use the windage adjustment on the top of the scope to adjust it accordingly. You will remove the cap from the windage adjustment and you will turn the windage adjustment. For instance, if you missed left, you need to turn the adjustment so that the lens of the scope moves slightly to the left.
Each click of the windage adjustment equals 1/20th of an inch, so 20 clicks will equal 1 inch.
Continue this process until your shots consistently land on the vertical strip of tape.
Step 3: Adjust the Elevation
Once you have the windage set right, you can do the same with the vertical alignment, or elevation. Basically, repeat the process above, this time moving the elevation adjustment on the side of the scope until you can consistently hit the cross you made with the tape. If you're hitting below that point, turn the knob so that the scope lens moves down and vice versa.
Again 1 click equals 1/20th of an inch, so move it 20 clicks to move it an inch, and so on.
Step 4: Repeat With Other Reticles
The most important reticle to sight in is the shortest, most prominent one, normally corresponding with 20 yards. However, it's worth it to measure out the distance for the other reticles and take some shots.
If you have a speed dial scope, you should be able to hit the center point of your cross from each distance no problem. If not, there's likely a problem with your speed setting and you need to repeat step 0.
Otherwise, the shots for the other reticles will probably be slightly off if you're using a bolt-broadhead combination with a different weight than the crossbow was rated for. In this case, as long as the shortest reticle is hitting accurately, do not adjust the scope for the lower reticles. Instead just take note of how far off the shots are landing and aim accordingly in the field.
Sighting In Your Crossbow in the Field
It's difficult to sight in your crossbow in the field. For one thing, you have nothing to shoot it at, and even if you did, the noise could ruin your hunt. That said, while fully sighting in your crossbow in the field is not really practical, many bowhunters do make slight adjustments based on the conditions they encounter, namely the wind and elevation, hence the names of the adjustment knobs in the first place.
Field Adjustment for Windage
Strong lateral winds inevitably affect the trajectory of your arrow. For instance, a wind blowing to your left will move the bolt to the left of your aim.
To account for that, you have to pivot the crossbow more to the right. Some bowhunters prefer to just aim the scope slightly to the right while others like to actually adjust the scope so the reticle is on target. To do this, you turn the lens in the direction of the wind.
Field Adjustment for Elevation
You're likely hunting from a tree stand, so you'll be elevated off the ground. One paradox of bowhunting most archers are unaware of is that regardless of your elevation, positive or negative, the greater the angle of your shot away from horizontal, the more you will have to adjust your aim down. In other words, if you're shooting 30 degrees upwards towards a target or downwards, you will have to aim lower.
This is because any angle away from horizontal shortens the ground distance versus the bolt's distance to the target. While your quarry might be 20 yards away according to your range finder, if you're 20 feet up in a tree stand, the bolt will actually cover less than 20 yards of ground before hitting the deer. This means it will drop less than when you sighted it in and hit higher than what you were expecting. The same is true if you're shooting from 20 feet downhill.
Again, some hunters learn to eyeball this while others like to do the math and actually adjust the scope in the field.
Technology has come a long way with crossbow scopes and there are now angle compensating crossbow scopes with built in rangefinders that take all of the guesswork out of shooting angles.
Try It at Home
It doesn't matter if you have a cheap crossbow or a high end model, we recommend trying your field adjustments at home first. Try shooting in the wind or from a higher elevation to see how much it throws off your shot. This will give you a better idea of how much you need to adjust your aim or the scope, and you can practice doing it so that you're more accurate in the field.
The key to keeping your crossbow scope sighted in is to always properly maintain and store your crossbow when not in use.
This will help keep your crossbow scope zeroed in for years to come.