Bore sighting a red dot is a fast and popular way to get your optic roughly aligned with your firearm before live-fire zeroing. But how accurate is it — and what should you realistically expect from the process? This guide explains what bore sighting does (and doesn’t do), common methods, practical accuracy expectations, and a safe workflow to get on paper quickly and efficiently.

What bore sighting actually accomplishes

Bore sighting places the optical axis of your sight roughly in line with the barrel axis so the bullet will land on paper at a short distance. It’s a coarse alignment step — a time-saving shortcut that reduces the number of rounds needed to get on target when you finish with live fire. It does not replace shooting and fine-tuning your zero with live rounds.

Expected accuracy — realistic numbers

  • Short range (10–25 yards / meters): Bore sighting will commonly get you within a few inches of point of aim at these distances. That’s usually good enough to place your first group on paper.

  • Mid range (50–100 yards): The alignment error from bore sighting quickly magnifies with distance. Expect several inches to a foot or more of shift at 50–100 yards depending on method quality and rifle/optic geometry.

  • Practical takeaway: Bore sighting is usually accurate enough to get you on paper and into the target area at typical zeroing ranges, but don’t expect moa-level precision. Live-fire adjustments are always required to dial in a true zero.

Factors that affect bore sighting accuracy

  1. Method used: Laser bore sighters are generally more precise than eyeballing through the bore. Using a chambered round (pointing the rifle at a distant target and centering the bore) can be more accurate than simply looking down the barrel.

  2. Quality of the red dot and mount: Optic tilt, loose mounts, or low-quality manufacturing increase error.

  3. Parallax and eye position: Although most red dots are effectively parallax-free at typical engagement ranges, inconsistent cheek weld and eye alignment during bore sighting can introduce error.

  4. Barrel/optic alignment: Some rifles/optic combos have an inherent offset (sight height, cant, or barrel harmonics) that makes a pure bore alignment less accurate at distance.

  5. Distance to target during bore sighting: The farther the target used for bore sighting, the smaller the angular error appears; but practical constraints often limit how far you can safely bore sight.

Common bore sighting methods

1. Laser bore sighter

  • How it works: Inserted into the chamber or clamped in the bore, the laser projects a dot on a target. Adjust the red dot to coincide with the laser dot.

  • Pros: Quick, repeatable, and safer than trying to look down the bore at a distant target.

  • Cons: Quality varies — cheap lasers can be misaligned within their shank, so verify with a second method if possible.

2. Boresighting by eye (through the bore)

  • How it works: From a stable rest, remove bolt (if safe/legal), look through the bore and center a distant target, then adjust the red dot to match.

  • Pros: No special tools required; can be quite accurate at short distances.

  • Cons: Requires removing the bolt on many rifles, and human error/eye position can reduce precision.

3. Chambered round method

  • How it works: With a live round chambered and the rifle pointed at a safe backstop at distance, align the bore visually and then set the optic. (Follow all safety rules.)

  • Pros: Can be accurate because you’re aligning with the actual chambered round position.

  • Cons: More risk if not done with extreme caution — many shooters avoid this unless on a proper range and trained.

Best practice workflow for bore sighting a red dot

  1. Secure the firearm: Use a stable rest or vise and follow all safety rules (unload, safe direction, finger off trigger when manipulating).

  2. Choose a method: Laser bore sighter is simplest for most users. If boresighting by eye, remove the bolt if applicable and ensure stable head position.

  3. Start close: Begin at 10–25 yards to get on paper quickly.

  4. Make coarse adjustments: Move the red dot to the bore dot or centered view.

  5. Move to the range: Fire a 3-shot group at your intended zero distance and translate measured offsets into clicks.

  6. Fine-tune: Use live rounds to finalize the zero — bore sighting is only the preparatory step.

Safety notes

  • Always treat the firearm as loaded when necessary and follow range rules.

  • Never point at anything you are not willing to shoot.

  • When using lasers, follow manufacturer instructions and ensure batteries/fit are stable.

Conclusion

Bore sighting a red dot is a useful and time-saving preliminary step that reliably gets you on paper and into the target area. However, it is not highly precise at full engagement distances — expect to use live fire for final zeroing. Use a good quality laser or a careful bore-through method, keep everything rigid and repeatable, and always finish the job at the range with real rounds.