How to Zero a Thermal Scope: Step-by-Step Guide (Day & Night)

You just dropped a serious amount of money on a new thermal optic. You mounted it, headed out to the field, spotted a massive boar at 75 yards, pulled the trigger... and watched the dirt explode three feet behind him.

The most advanced thermal sensor in the world is completely useless if your rifle isn't properly zeroed. While the basic principles of sighting in a rifle remain the same, thermal scopes require specific targets and techniques—especially if you want to zero them while the sun is still up.

Whether you are running an ultralight setup or a flagship model, this guide will teach you exactly how to sight in a thermal scope quickly, accurately, and without wasting a box of expensive ammunition.

Quick Answer: Sighting In a Thermal Scope

To zero a thermal scope:

1. Mount the rifle securely on a stable rest.

2. Set up a thermal-reactive target (like a heated foil square or hand warmer) at 50 or 100 yards.

3. Fire a single, highly controlled shot at the center of the target.

4. Keep the rifle perfectly still, open the zeroing menu, and use the "Freeze Frame" or "One Shot Zero" feature.

5. Move the digital reticle from the center of the target directly over the bullet hole. Save and confirm.

What You Need Before You Start

Do not head to the range unprepared. You will need:

• Your rifle and securely mounted thermal scope.

• A highly stable shooting rest, lead sled, or sandbags (stability is critical for digital zeroing).

• Your chosen hunting ammunition (do not zero with cheap plinking ammo).

• Thermal Targets: Thermal scopes cannot see ink on paper. You need something that emits or reflects heat.

  • Pro Tip: You can buy dedicated ATN Thermal Targets, use activated hand warmers taped to a cardboard box, or use squares of aluminum foil angled slightly upward to reflect the cold sky.

Can You Zero a Thermal Scope During the Day?

A very common question is: can you sight in a thermal scope during the day? Yes, absolutely.

Thermal scopes do not rely on visible light; they read temperature differentials. As long as your target is noticeably hotter or colder than the background, your scope will see it.

Daytime Zeroing Tips:

• If you are shooting in the heat of the day, the sun will warm up the backstop, making targets harder to see. Use an ice pack wrapped in duct tape as a "cold" target. Set your scope to "Black Hot" or "White Hot" depending on which provides the best contrast.

• Aluminum foil works incredibly well during the day because it reflects the ambient temperature of the sky, creating a stark contrast against a warm dirt berm.

Step-by-Step: How to Zero a Thermal Scope

Follow these steps precisely to learn exactly how to zero a thermal scope without wasting ammo.

Step 1: Set Up at the Proper Distance

For most hunting applications (especially hogs and coyotes), a 50-yard or 100-yard zero is ideal. Set up your thermal target against a safe backstop. Ensure the heat source is clearly visible in your viewfinder.

Step 2: Stabilize the Rifle

Your rifle must be absolutely immobile. If you are wobbling off-hand or using a flimsy bipod, this process will not work. A lead sled or heavy sandbags are highly recommended.

Step 3: Take the First Shot

Aim dead center at your thermal target. Focus on your breathing and trigger pull. Fire one single, highly controlled shot.

If your shot is not on paper at all, move the target up to 25 yards to get on paper, zero it there, and then move back to 100 yards.

Step 4: Freeze the Image / Open Zeroing Menu

This is where modern thermals shine. Navigate to your scope's "Zeroing Setup" menu.

• Ensure your crosshairs are aimed exactly where you aimed during Step 3 (the center of the target).

• Activate the "Freeze Frame" or "Zeroing Freeze" feature. This takes a snapshot of the screen, allowing you to take your hands off the rifle without losing your alignment.

Step 5: Move the Reticle to the Impact

Looking at the frozen screen, you will see your original crosshair (the center of the target) and the actual bullet hole (which should be glowing hot from the friction of the bullet hitting the backstop).

• Use your scope's control wheel or buttons to move the secondary reticle away from the center of the target and place it perfectly over the glowing bullet hole.

• Save the profile. Your scope has now digitally aligned the crosshairs with the actual point of impact.

Step 6: Confirm with Follow-Up Shots

Exit the zeroing menu. Fire a 3-shot group at the center of the target. All three shots should now cluster directly where you are aiming.

How to Bore Sight a Thermal Scope (Optional but Helpful)

If you are mounting a brand new scope, you might not even hit the paper on your first shot. This is where you need to know how to bore sight a thermal scope.

1. Remove the bolt from your rifle (if it is an AR-15, separate the upper receiver and remove the BCG).

2. Set the rifle in a stable rest and look directly down the barrel from the chamber end. Center the barrel on your target at 25 or 50 yards.

3. Without moving the rifle, look through the thermal scope.

4. Go into the zeroing menu and move the reticle until it is centered on the same target you see through the barrel.

5. This will get you "on paper," allowing you to proceed to Step 3 above.

Night Zeroing vs. Day Zeroing

While you can zero during the day, many hunters prefer to wait until dusk or full night.

At night, the ambient temperature of the environment drops significantly. When you put a heated target (like a hand warmer) against a cool background, the thermal contrast is massive. This makes it incredibly easy to see the exact center of your target and the glowing heat signature of your bullet impacts. If you are struggling with contrast during a hot afternoon, wait until the sun goes down.

Common Mistakes When Zeroing Thermal Scopes

If you are struggling to figure out how to zero thermal scope systems effectively, you are likely making one of these errors:

• Chasing Shots: Firing a shot, moving the reticle, firing another shot, moving the reticle again. Use the Freeze Frame feature. It requires one good shot and one adjustment.

• Zooming in Too Far: Digital zoom pixelates the image. If you zoom in to 16x on a budget scope, the target will become a blurry block, making precise aiming impossible. Zero at your base magnification or the lowest zoom possible.

• Using the Wrong Target: Spray painting a dot on a piece of cardboard does not work. You must have a temperature differential.

Tips for Better Accuracy

• Use Consistent Ammo: Zero with the exact ammunition you plan to hunt with. Different grain weights and bullet types will have drastically different points of impact.

• Let the Barrel Cool: Firing 10 rounds rapidly will heat up your barrel, which can cause the point of impact to shift.

• Understand Your Ballistics: A 50-yard zero on a .308 will impact differently at 200 yards than a 100-yard zero. Know your bullet drop.

Product Notes for Easier Zeroing

Modern optics have made this process incredibly user-friendly:

• ThOR 6 Series: These flagship models feature an advanced "Zeroing Setup" menu with "Zeroing Freeze," making the one-shot zero process virtually foolproof. They also allow you to save multiple profiles for different ammunition types.

• ThOR 6 Mini: Even though it is a compact, budget-friendly option, the Mini still includes the digital Zeroing Freeze feature, allowing beginners to zero their rifles quickly and easily.

• TICO 6 (Clip-On): If you are using a clip-on thermal, the process is different. The TICO 6 is factory collimated. You do not zero the thermal; you rely entirely on the existing zero of your daytime glass.

Frequently Asked Questions

How do you sight in a thermal scope?

You fire one controlled shot at a thermal-reactive target, freeze the screen in the zeroing menu, and digitally move the reticle from your point of aim to your actual point of impact.

What distance should I zero a thermal scope at?

For most night hunting (hogs and coyotes) using calibers like 5.56, 6.5 Grendel, or .308, a 50-yard or 100-yard zero is the standard recommendation.

Is it better to zero at night?

It is often easier to zero at night because the cooler ambient temperatures provide a starker contrast against heated targets and glowing bullet impacts.

Can thermal scopes hold zero?

Yes. Quality thermal scopes, when mounted properly to a torqued Picatinny rail, will hold zero just as reliably as high-end traditional daytime glass.

Conclusion

Learning how to properly sight in your thermal optic is the most important skill you can master before heading out into the dark. By using the right thermal targets, utilizing the Freeze Frame feature, and ensuring your rifle is absolutely stable, you can achieve a perfect zero with just two or three rounds.

Take the time to verify your zero at the range, confirm your ballistic drops, and you will step into the woods with the confidence that when the crosshairs are on the target, the pig is going down.