How to Use a Boresight to Zero Your Rifle Scope
By Optics Force | Published: 2026-10-18
Category: How-to Guides
Learn how to quickly zero your rifle scope using a laser boresight. This step-by-step guide covers chambering, adjusting, and verifying your zero with minimal ammo waste.
Quick answer
A laser boresight saves time and ammunition by projecting a visible dot onto your target, letting you align your scope before firing a single shot.
Why use a boresight instead of shooting to zero?
Traditional scope zeroing can burn through a box of ammo just to get on paper. A boresight cuts that down to a few confirmation shots. It also reduces barrel wear and range time.
The trade-off: a boresight aligns your scope at a short distance (typically 25–100 yards). You still need to fire live rounds to fine-tune for your exact load and environmental conditions.
Choose the right boresight for your caliber
Boresights are caliber-specific. Using the wrong size can damage your chamber or produce an inaccurate reference point. Always match the cartridge designation printed on the boresight to your rifle's chamber.
For example, the Sightmark 12Ga Boresight is designed for 12-gauge shotguns, while the Sightmark .243, .308, 7.62x54 Boresight covers multiple popular rifle calibers. The Sightmark .300 Boresight is made for .300 Win Mag rifles. Check your barrel's stamp before buying.
How to zero your rifle scope with a boresight
- 1. Safety first — clear the rifle: Ensure the rifle is unloaded. Remove the magazine and check the chamber. Point the muzzle in a safe direction. A loaded rifle with a boresight can cause injury or damage. Always double-check.
- 2. Insert the boresight into the chamber: Gently push the boresight into the chamber like a regular cartridge. Close the bolt or action. The laser should turn on automatically (some models have a separate switch). If the laser doesn't light, check the batteries. The Sightmark models use AG3 or AG5 batteries — verify the correct type for your unit.
- 3. Set up your target at a known distance: Place a target at 25 or 50 yards. The closer distance makes the initial adjustment easier. Aim the rifle at the target using a rest or sandbag. A 25-yard zero will shift at longer ranges, but it gets you on paper fast. Plan to confirm at your intended zero distance later.
- 4. Align your scope reticle with the laser dot: Look through the scope and locate the red laser dot on the target. Without moving the rifle, adjust your scope's windage and elevation turrets until the crosshairs sit exactly on the dot. Turn turrets in the direction indicated (e.g., 'R' for right). A common mistake is turning the wrong way — go slow and check each click.
- 5. Remove the boresight and fire a confirmation group: Eject the boresight carefully. Load a single round and fire at the target. The shot should land close to your point of aim. Adjust your scope as needed and fire a three-shot group to confirm zero. Your first shot may be off by an inch or two — that's normal. Fine-tune with small turret adjustments (usually 1/4 MOA per click).
Product facts
- Sightmark 12Ga Boresight: At 100 yards, the device will project a 2-inch image on paper, saving you money on ammunition. This means you can get a rough zero quickly without firing a shot, then confirm with just a few rounds.
Sightmark 12Ga Boresight - Sightmark .243, .308, 7.62x54 Boresight: Chamber the boresight in your .243, .308 or 7.62x51 rifle like a regular cartridge, and a red laser dot shows exactly where you're aiming. It works like a dummy round, so you can safely chamber and eject it multiple times during the setup process.
Sightmark .243, .308, 7.62x54 Boresight - Sightmark .300 Boresight: Includes a carrying case, three AG3 batteries, and instructions. Everything you need is in the box — no separate battery run or storage case to buy.
