How to Sight In a Crossbow Scope

Quick answer

Sighting in a crossbow scope is a short, repeatable process. You start close so the first bolt lands on paper, then move to 20 yards and shoot groups, not single shots, until the group sits on the bullseye. Most crossbow scopes use a 20-yard top reticle with extra lines or a dial for 30, 40 and 50 yards, so the 20-yard zero is the one that matters most.

• Mount the scope level with the rail and tighten the rings evenly.
• Bore-sight at 10 yards so the first shot lands on the target.
• Zero the top reticle at 20 yards with three-shot groups.
• Confirm each extra reticle line or dial setting at its real distance.
• Decock at the end of the session. Never walk downrange with the crossbow cocked.

If you are new to crossbows, read how far a crossbow will shoot first. It sets realistic distance limits before you start chasing 50-yard groups.

What do you need to sight in a crossbow?

You do not need a lot of gear, but each item on this list solves a problem you will otherwise blame on the scope.

• A target rated for crossbows. Crossbow bolts carry more energy than most vertical bow arrows. A bag or foam block that is not rated for crossbows can let a bolt pass through, or bury it so deep that you damage the vanes pulling it out.
• A bench, sandbag or shooting rest. Your goal is to test the scope, not your offhand steadiness. A rest under the fore-end removes most human error from the group.
• The tools for your scope rings. Usually a Torx or hex key. Check the ring screw size in the manual before you get to the range.
• Bolts with matched field points. Use the same point weight you will hunt with, normally 100 or 125 grains. Six bolts of the same length and weight are enough. Our crossbow bolt weight chart explains how to match them.
• A decocking method. Either a crank with a decocking function, a decocking bolt, or a discharge target. Know which one your manual allows before you cock the bow.
• A cocking aid. A rope cocker or crank gives you the same string position every shot. This matters more for accuracy than most people expect. See our guide to crossbow cocking devices.

How do you mount a crossbow scope correctly?

Most crossbows ship with the scope already in the rings. Even so, check the mount before you shoot. A scope that shifts in loose rings will never hold zero, and you will spend the whole session chasing it.

Rings tight and even

Snug the ring screws in a cross pattern, a little at a time, so the gap on each side of the ring stays equal. Most makers list a torque value in the manual, often in the range of 15 to 25 inch-pounds. Do not use thread locker unless the manual says to.

Scope level with the rail

The vertical crosshair must line up with the center of the rail. If the scope is rotated even a few degrees, your windage will be right at 20 yards and wrong at 40, because the drop lines no longer sit over the bolt's path. Rest the crossbow on a flat bench, put a small bubble level on the rail, then a second level on the top turret cap, and rotate the scope until both agree. The same idea applies to vertical bows, and our guide on how to level a bow sight explains the second-axis and third-axis logic in more detail.

Eye relief

Shoulder the crossbow with your cheek on the stock the way you will shoot it. Slide the scope forward or back in the rings until you see a full, sharp picture with no black ring around the edge. Crossbow scopes usually have 3 to 4 inches of eye relief. Set it once, then tighten the rings.

How do you bore-sight a crossbow at 10 yards?

Bore-sighting means getting the scope roughly in line with the rail so the first shot lands on paper. Crossbows do not have a barrel you can look down, so you do it with a shot at close range.

1. Set a large target with a clear aiming dot at 10 yards. Use a fresh face so you can see every hole.
2. Cock the crossbow with your cocking aid, load a bolt, and shoot one shot from the rest using the top reticle.
3. Note where the bolt hit. At 10 yards, a bolt that lands 2 inches low and 1 inch left tells you the scope needs to come up and right.
4. Make a large adjustment, roughly double what you would use at 20 yards, then shoot again.
5. Once the bolt lands within about 2 inches of the dot, move the target to 20 yards.

Some scopes come with an adjustment chart printed on the turret caps. Check the direction arrows. On most scopes, turning the turret in the direction marked UP moves the point of impact up, not the reticle.

How do you zero a crossbow scope at 20 yards?

This is the step that decides everything else. Take your time, shoot groups, and only adjust after a group, never after one bolt. One bolt tells you about that bolt. Three bolts tell you about the scope.

Click math for 1/4 MOA and 1/2 MOA scopes

Crossbow scope turrets adjust in minutes of angle. One MOA is close to 1 inch at 100 yards, which means only 0.2 inches at 20 yards. So a 1/4 MOA click moves the impact 0.05 inches at 20 yards, and a 1/2 MOA click moves it 0.1 inches. Beginners are often surprised by how many clicks a small correction takes.

Check the turret cap or manual for your scope's click value. Some crossbow scopes use 1/20-inch-at-20-yards clicks, which work out the same as 1/4 MOA.

How do multi-reticle and speed-dial scopes work?

Almost every crossbow scope has more than one aiming point. The two common designs behave differently, so it pays to know which one you have.

Multi-reticle scopes

These have a top crosshair for 20 yards and extra lines or dots below it, usually for 30, 40 and 50 yards. The spacing between lines is fixed. The maker chose it for a certain bolt speed, often 300 to 350 fps. If your crossbow is faster or slower than that, the 20-yard zero is still correct but the lower lines will be a little off. That is why you confirm each line at its real distance.

Speed-rated and speed-dial scopes

These have a ring or a dial marked in feet per second. When you set it to your crossbow's real speed, the scope changes magnification so the reticle lines match your bolt's drop. The important word is real. The speed printed on the box was measured with the lightest bolt the maker allows. If you shoot a heavier hunting bolt, your speed is lower and the dial must be set lower. Shoot through a chronograph if you can. If not, use the arrow kinetic energy calculator to estimate speed from your bolt weight, then fine-tune the dial by shooting at 40 yards.

How much does a crossbow bolt drop past 20 yards?

A crossbow bolt is heavy and slow compared with a rifle bullet. Drop grows fast past 30 yards, which is why the lower reticle lines sit so far below the top crosshair. The table gives typical drop from a 20-yard zero for three common speeds. Your numbers will vary with bolt weight, vane size and the exact height of the scope above the rail.

Approximate drop below the 20-yard zero. Use it to sanity-check your reticle, not as a substitute for shooting at each distance.

Confirm at each distance

After the 20-yard zero, move the target to 30 yards and shoot a three-shot group using the 30-yard line. Then 40, then 50. If a group is high or low on a fixed multi-reticle scope, do not touch the turrets. The 20-yard zero is correct and the reticle spacing is simply not matched to your speed. Write down the real hold for each line and tape it to the stock. On a speed-dial scope, nudge the dial up if you are hitting high at 40 yards, or down if you are hitting low, then re-check 20 yards. Our archery target distance chart lists sensible practice distances for each level.

Why won't my crossbow group or hold zero?

When groups open up or wander, the scope is usually the last thing to blame. Work through the table from top to bottom.

Most zero problems come from the mount, the cocking or the bolts, in that order.

How often should you re-check a crossbow zero?

A well-mounted scope on a modern crossbow holds zero for a long time. Even so, re-check it in these situations:

• Before every hunting season, and again after any rough transport.
• After you change the string or cables, or after the bow has been serviced.
• After switching bolts, points or broadheads.
• Any time the crossbow is dropped or bumped hard, even if nothing looks bent.
• Every 100 to 200 shots as a habit, with one three-shot group at 20 yards.

Broadheads vs field points

Zero with field points first because they are cheap and fly cleanly. Then shoot a group with the broadheads you will hunt with. Fixed-blade heads often hit an inch or two away from field points at 20 yards, and the gap grows with distance. Mechanical heads usually match field points closely. If the broadhead group is off, you have two choices: re-zero for broadheads and accept that field points will now hit slightly off, or fix the underlying bolt flight so both land together. Never hunt on a field-point zero you have not confirmed with broadheads. Browse our crossbow guides for more on bolts and heads.

Related guides

These pages cover the other parts of setting up a crossbow for accurate shooting.

References

These sources support the guidance on this page.

• TenPoint Crossbow Technologies: owner's manuals and scope instructions
• Ravin Crossbows: manuals and sighting-in guidance
• Excalibur Crossbow: owner's manuals and scope setup
• Barnett Crossbows: product manuals
• Illinois Department of Natural Resources: hunting regulations and equipment rules