A familiar situation: the new rifle is in the house, and so are the optics intended for it. You mount the combo yourself, while the anticipation of the first shooting range visit rises and rises. But one thought clouds this anticipation for many shooters: it is still absolutely unclear where the first shot will land, and sighting in presents a problem – after all, you don't want to take any safety risks at the range or waste ammunition unnecessarily. For more safety and above all for saving many cartridges, there are various aids. A boresight is one of them. These devices project a laser beam onto the target, which then allows the shooter to pick up the potential aiming point through the optics and adjust the latter accordingly. One of these devices is the Boresight series from Sightmark.
Sightmark Boresight: the practical laser aid
The Sightmark Laser Boresight is inserted into the chamber like a cartridge. The alternative here would be a device that can be mounted on the muzzle. Sightmark also offers such a device, which is available in the green laser version in addition to the red laser one. This offers the advantage of greater flexibility, since it is caliber-independent, but it is not as accurate.
Our Sightmark Boresighter came in .243 Winchester caliber, which also covers .308 Winchester. This works because the .243 is a necked down .308 and in this case the diameter of the case neck is of course irrelevant. The Sightmark Laser Boresight is offered off the shelf for all popular rifle calibers up to 9.3x62 mm. As for our device, it is often suitable for multiple, related calibers. In addition, Sightmark also offers it for 12-gauge shotgun shells and handguns in 9mm Luger, .45 ACP and .357 Magnum /.38 Spl. Among the calibers are, of course, all the popular hunting and sporting calibers such as the .223 Remington, the .30-06 Springfield or the 8x57IS.
Outwardly, the device comes in the form of a cartridge case, which means that a bullet is missing. At the end of the "cartridge" sits a slightly enlarged extractor groove, so you don't have to make any effort here to get the device back out of the chamber after optics adjustment. There is no primer or dummy for it either. Of course, such a boresighter is not made for dry firing. The laser diode, which is responsible for projecting the illuminated dot onto the target, is located in the neck of the case. According to the manufacturer, the power is enough to see the dot on the target at up to 90 meters.
Two AG5 batteries, or alternatively three AG3 batteries, are required for the power supply. They find their place on the back. To insert them, the user simply unscrews the cartridge base. The device is also switched on and off in this way: if batteries are inserted, the laser is active. To turn it off, they must be removed again.
Sightmark Boresight technical specifications and price
| Model: | Sightmark Boresight |
| Caliber: | .243 Winchester (also suitable for .308); many more
calibers available |
| Laser Wavelength (nm): | 632-650 |
| LED Type: | Visible red laser |
| Visibility: | Up to about 90 meters |
| Dot Size: | About 2”/5 cm at 90 meters |
| Operation: | On / off end cap |
| Material: | Brass |
| Operating Temperature: | -10°C to 50°C |
| Output Power: | <5 mW |
| Battery Type: | Two AG5 or three AG3 |
| Battery Life: | One hour approx |
| Price: | 41.99 euro |
Function and practical use
The principle of the Boresight is analogous to the traditional "looking down the bore", which is familiar to many shooters. The bolt is removed and the barrel bore is aligned to a predetermined point. The optic are then also aligned with this point. However, laser technology is much more accurate: it not only allows rough sighting in, but also fixes the alignment of the bore axis to a very small dot. In this way, the shooter ends up much closer to the actual point of impact than with the naked eye. Experience shows that the latter is often more art than science. But beware: even a boresight cannot outsmart physics. While a laser beam always runs absolutely straight, the bullet flies along a ballistic curve. Even if this does not cause particularly large deviations, especially with fast calibers, the user should bear that in mind.
In practical use, safety comes first, of course: before adjusting the optic with the device, a gun safety check should be performed. Once this is done, the shooter can prepare the Boresight. To do this, he/she inserts the batteries mentioned above. The Boresight is then inserted into the chamber like a cartridge. The bolt does not have to be closed, but it can be. From this moment on, the gun already projects the point of impact onto the target. The distance at which the gun is fired also depends on the subsequent firing distance. The manufacturer recommends a 25-yard distance as standard. This is 23 meters, and the deviation from the 25-meter shooting range would probably be negligible. The actual point of impact on the 100-yard range (90 meters) should then be within ten centimeters of the aiming point. Somewhat closer to the target – depending on the caliber – is achieved if the optics are positioned slightly above the laser. In the process, the shooter then ideally fixes his gun or at least uses a forend and butt rest – this makes it easier. Then all he/she has to do is align the optic of his choice with the laser dot on the target. Once that's done, the subsequent sighting in should be done safely and with just a few rounds.
Finally, a tip: apart from shooting in, the Sightmark Boresight can also be used excellently for target practice. The permanently visible laser dot means that the shooter always has the potential aiming point in view. This is a great help, for example, when practicing swings for target shooting.
The Sightmark Boresight comes in a practical Cordura pouch. This not only provides space for two of the devices, but also for the batteries. Price in EU is €41.99.
