How to sight a crossbow

by Steve Coffman, last updated on

Learning how to sight a crossbow isn’t as straightforward as you’re made to believe in movies. You want to take down the game in a clean, safe, and humane way. You don’t want to damage game meat, nor do you want to injure people around. You want a clean shot – “one shot, one kill” as Tom Berenger would famously put it. What you want is a sniper-like accuracy – a clean, fuss-free job. That’s it!

But achieving dead-on accuracy with a crossbow is unlike a rifle. If you get it wrong, you can get frustrated when you lose your target. Learning how to aim a crossbow is more of a technique than the scope, but some scopes can let you down no matter how skilful you’re. Wind, aerodynamic drag, gravity and elevation can make aiming more complicated, because they affect the downrange flight of arrows. Besides, targets can be harder to take down if they run, spring or panic as a result of spotting you. For a starter, taking all these factors into account may seem overwhelming.

Things to Consider

There are four things you need to consider before you sight in a scope to your crossbow:

  • Model of a scope
  • Adjustment knobs
  • Scope’s specifications
  • Scope’s optics

Don’t Forget to Carry the Following Equipment

Make sure you’ve the following when calibrating the sight of your crossbow:

  • Scope manufacturer’s manual
  • A tripod to remove shaking
  • Arrow rest to increase balance and reduce torque and vibrations
  • At least four arrows
  • A bull’s eye or a non-moving target

But first things first. Before you sight in a scope to a crossbow, make sure you mount the scope on the device correctly. To determine whether mounting is correct, place the crossbow on your shoulder. 

If you find that you don’t need to move your head to look through a sight, and the field of view is clear, then the scope’s position is correct. If, on the other hand, the field of view is blurred or dark, then you’ll need to readjust the scope’s position.

It can take a lot of time to sight in a scope to a crossbow. If you haven’t been shooting for a long time, and you don’t have sufficient stamina and strength to aim sight for a long time, your arms and shoulders would tire. 

And so, you’ll have run out of patience before you realize, making you susceptible to firing inaccurate shots. Moreover, when you fire, you’ll experience recoil, torque and vibration. We recommend you use a shooting aid like an arrow rest and a tripod.

How to Aim a Crossbow in Steps?

  • First, fix a tripod 20 yards away from the target and mount a crossbow on it. If you don’t have a tripod, move backwards from a target until you reach the 20-yard mark.
  • Cock the crossbow by placing an arrow in position and pulling back a cocking string or a cranking aid toward an anchor point.
  • Aim your sight by looking through the scope. Make sure the top reticle is in line with the bullseye. Use your finger to pull the trigger. Avoid pulling the trigger by holding with your palm as too much force can decrease accuracy. Repeat the cocking and firing process for two more arrows.
  • Check the position where the three arrows are lodged in the target areas around the bull’s eye. How close or far did you miss the bullseye? Take note of the range within which the arrows have landed from the bullseye. (We don’t expect you to hit the bullseye at this point). If you used tight groupings of arrows, then we expect that the arrows are lodged in the target areas near each other, perhaps within two-inches from each other. Adjust the knobs, so next time you fire, you hit the bullseye perfectly. (We’ll delve into how to make adjustments for wind and height shortly afterward).
  • Set up the crossbow once more 20 yards away from the target. Repeat the cocking and firing process. Check the positions and groupings again. If all the arrows hit the bullseye, then your scope is correctly calibrated. If not, repeat the process until you get positive results.

Now that you’re aware of the steps, let’s take a look at how to adjust the knob and reticles.

How to Adjust Reticles and Knob for Greater Accuracy

The top reticle must be at “zero”. If not, you’ve to align “zero” with the top reticle. The “zero” is the topmost reticle or dot. And so, if you want to calibrate the sight of your scope to fire arrows 20 yards from the target, then you should align the 20-yard reticle with the zero.

adjust reticles

Most scopes come with a 20-yard reticle as the topmost calibration mark. The lower-yard reticles: 30, 40, 50 and 60 will align automatically for respective yardages.

Most crossbow hunters prefer three-reticle scopes. A scope with a single reticle requires you to sight only one yardage. Anything more than three reticles is excess, as your crossbow may lack sufficient power to guarantee hitting a target at greater distances than 40 yards.

Adjustments for Wind and Height

A scope has two adjustable knobs:

  • Wind
  • Height

The first time you fired arrows you missed the bullseye by a margin, because of the effects of wind and height, which you didn’t take into account. The scope has knobs, so you can adjust it for wind and height.

Wind Adjustment: Wind affects the downrange flight of arrows. If your arrows flew way off from the bullseye, it’s possible that wind diverted them. The stronger a wind, the more the diversion. Turn the wind adjustment knob clockwise if the arrows landed on the left area far away from the bullseye. Turn anticlockwise if the arrows landed on the right area far away from the bullseye.

When you turn the knob, you’ll hear a click sound. Every time you hear a click sound, the knob has rotated by 1/20 of an inch for a 20-yard reticle. You’ve to hear 20 clicks for 1-inch. And so, if arrows landed at positions that are within 3-inches from the bullseye, rotate the windage knob until you hear 60 clicks.

Height Adjustment: If arrows landed at a range of distances above or below the bullseye, you need to make adjustments for height. For arrows which hit areas above the bullseye, turn the height adjustment knob anticlockwise to cause them to hit lower areas. Turn clockwise to cause arrows to hit areas above if they landed at lower areas. 

And so, if the arrows landed in an area within 2-inches above the bullseye, you’ve to rotate the knob anticlockwise until you hear 40 clicks.

So finally…

Learning how to sight a crossbow is a matter of adjusting the sight or aim of a scope for wind and height. The process is all about calibrating sight, so you can hit the bullseye or game accurately after adjustment. Make sure you follow manufacturer’s manual, and you’ve at least four arrows, a tripod, an arrow rest and a non-moving target or bullseye. Sighting a crossbow is a time-consuming process, so you’ve to be patient.

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