How To Zero The Laser Boresight To A Weapon

We’re going to do a talk through on how to zero the laser boresight to a weapon. If you have any questions on what this piece of kit is, and why it is important, check our TTP post from before.

The Laser Boresight can be used with regular 5.56mm, 7.62mm, and .50 caliber weapons, sniper weapons are excluded due to the nature of the rifling of their barrels. This system is unique compared to bullet-type lasers, in that it is zeroed to the individual weapon’s barrel. This means that you get closer to the true line of bore for that weapon.

To zero it, you will first select and screw in the appropriate mandrel by hand. Do not tool tighten the mandrel, as it will crack the nut loose from its polymer case, and then you have an LBS paperweight. You will then place it in the barrel of the weapon until the mandrel is snug against the crown of the barrel. Then you will ensure the weapon itself is stable. A rock-solid bench-rest type of position is preferred for the weapon, so that the soldier need not hold it at this point.

Once that is complete, you will begin to zero the laser to the weapon. Rotating the LBS in a counter-clockwise direction, you will start with the battery compartment facing up. Set the weapon up with a backstop of some sort at ten meters. If you look in the bag the LBS came with, there is a ten-meter string for measuring the distance out.

This takes two people to accomplish, the weapon man, and the target man. The target man places a zero mark (something as simple as a dot on a piece of paper) on true wall and calls out ‘half turn.’ This is the weapon man’s cue to turn the boresight 180 degrees.

What happens is that the laser from the boresight spins in an arc. The size of the arc depends on the barrel, and whether the LBS was mechanically zeroed (all the way clockwise, three turns counter clockwise) before use. Once the dot ceases movement, the target man talks the weapon man into making adjustments to the LBS (NOT the optic at this point) moving it to the reference point (an imaginary point halfway between the start point and half turn points). This is the true center of line of bore for this barrel.

Once that is completed, the Target man tells the weapon man to go to ‘start point’, which take the laser back the its beginning point. The target man has the weapon man keep refining the boresight zero until it spins on itself or a 1 centimeter circle. Preferably they will spin on itself, as that gets it closer to the true line of bore. Once that is completed, the laser is now boresighted to that weapon and ready to zero any optic, laser, or thermal. Picture four illustrates this.

So to sum up, we’ve discussed how to zero the boresight to the weapon. Next week, we’ll discuss how to use that zeroed LBS to zero the optic or enabler to that weapon.

#weaponsmastery #boresight

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Raymond Miller
82nd Airborne Division Small Arms Master Gunner: primary weapons trainer, force modernization for individual weapons, and range liason for the 82nd.