A LASER (Light Amplification by Stimulated Emission of Radiation) is a device for producing a coherent beam of light (often red or green for aiming aid systems) whose trajectory is a perfect straight line like the line of sight. Conversely, a bullet that leaves the muzzle of a gun describes a curved trajectory due to the Earth's attraction.
Since the LASER is most often mounted under the barrel of handguns, it should be noted that the beam will only cut the ballistic trajectory at one point.
It will have to be zeroed at a given distance in the same way as a more conventional pointing system (mechanical sights, red dot sights, optical systems, etc.).
But which distance to choose? How to proceed with this simplification? What are the parameters to consider?
The different adjustment protocols:
The "PVPT" (point targeted/point touched) is the most classic protocol. It simply repeats a procedure already perfectly known and mastered: the operator chooses a precise distance and then adjusts his laser so that its impacts coincide precisely with the point of the beam.
When choosing this option, the operator must know the difference between the target point and the point touched at all combat distances (whether these distances are greater or less than the zeroing distance).
What is more, before choosing this approach, it must be borne in mind that with this type of zeroing, the beam will be at certain engagement distances masked by the silhouette of the weapon. Therefore the shooter will be forced to change his firing position to see the point of the laser on his target. This modification of his posture may significantly change his gestures, his sensations, his reaction time (especially if he "seeks" his laser from the eyes)... and therefore overall its effectiveness.
This is the reason why another procedure, the "high" zeroing, noticeably finer and much less known, is used by some professionals.
The "high" Zeroing
This adjustment principle generally consists in associating the LASER with mechanical sighting devices.
It is done at a distance of 10m by simply bringing the LASER flush with the handlebars.
When zeroing the shooter adopts his usual shooting position, taking his aim in a conventional way. He changes absolutely nothing in his gestures.
This zeroing makes it possible to perfectly see the point of the laser above its mechanical sighting devices for any distance greater than or equal to 5m.
Below 5m, the point of the LASER remains hidden by the weapon but at these short and very short distances, with or without LASER, operators generally use shooting techniques that do not require "classic" aiming.
Up to twenty meters, a trained shooter will easily get a grouping the size of the palm of a hand, with a slight shift of impacts downwards as the distance increases.
Beyond twenty meters, the use of the LASER becomes more delicate. Indeed, the stabilization of the weapon is significantly more complex because of the movements of the LASER point on the target. A trained shooter will generally be more effective using their mechanical sighting devices. Nevertheless, the LASER option is still possible in many cases: difficult light conditions, non-academic shooting positions, shooting from a cover, etc ...
But in any case the shooter will have the advantage of keeping his sights as landmarks. It is also an advantage when several team members use LASERS simultaneously.
The use of the LASER corresponds quite well to what your reptilian brain will push you to do in combat (under intense stress): that is to say look at the threat, and open both eyes to capture as much information as possible.
With this type of setting, as you practice having your weapon (in general) and your sights (in particular) in your field of vision, all your gestures allow you to switch quickly, from one acquisition mode to another, if the situation requires it. In particular, in case of failure/breakage of your laser designator during the action, you only change the focus point / acquisition mode but all the rest of the firing sequence remains the same.
It has been found in some tests that a shooter equipped with a LASER generally wastes more time than a "conventional" shooter, when he went to look for the point on the target. This type of adjustment allows you to maintain the advantages of both approaches: kinesthetic appearance on one side and aiming on the other.
Finally, "high" zeroing also offers the significant advantage of being able to be carried out and then checked punctually without even having to shoot.
Note that at no time have we discussed in these lines the tactical aspect of the use of this type of aiming aid system. A subject in its own right that deserves special attention.