In-Chamber Laser Bore-Sighters
Boresighting the old-fashioned way — by looking down the bore of a rifle at a target — is not difficult. With a conventional bolt-action rifle, visual bore-sighting can be done quickly and easily: rest your gun securely on bags, remove your bolt and set up a 50-yard target with a large bright orange or black center circle. Look through the back of the action and you should be able to sight down the bore with your own eyes just fine. There’s no need for expensive hardware. In fact it may be easier to bore-sight the “old-fashioned way” rather than try to see a laser in bright sunlight at 50 yards (or even 25).
However, with lever guns and semi-auto rifles, including the popular AR15, M1 Garand, and M1A service rifles, the design of the receiver may make it virtually impossible to sight down the bore with the naked eye. That’s where a modern laser bore-sighting device comes in handy. For those situations where a bore-sighting tool is actually needed, we recommend a laser bore-sighter that fits inside your chamber. The in-chamber configuration is more fool-proof, and is inherently safer.
In-Chamber Laser Should Be Safer
Among the laser bore-sighters available on the market, we strongly favor those that fit in the chamber, rather than in the bore. With muzzle-entry laser bore-sighters, you could have a nasty accident if you forget to remove the device. There is always the chance you could chamber and fire a round with the muzzle-entry bore-sighter still in place. Instant Kaboom. That has happened more than once. With an in-chamber bore-sighter, there is no possibility you could chamber a loaded round with the bore-sighter in place. That’s an important safety advantage. The LaserLyte K-50 in-chamber bore-sighter is shown in the video below. You can see that, with the bore-sighter in place, you cannot chamber a live round.
In-Chamber Bore-Sighters for Rifles
We are pleased that companies such as LaserLyte has developed compact laser bore-sighters that fit inside your firearm’s chamber. The laser is housed in a brass assembly machined to duplicate a loaded cartridge. To activate the laser, simply place the bore-sighter in the rifle’s chamber and close the bolt. There are two core units, the Laserlyte Premium .223 (collimated lens $99.00) and the Pro .223 (standard lens $69.99). Both the Premium and Pro bore-sighters fit a .223 Rem, but they can be adapted to other chamberings by adding a caliber-specific sleeve over the .223 core unit. In addition, LaserLyte makes separate in-chamber bore-sighters for the 17HMR and 50 BMG.
Adapt Basic Unit to other Calibers with SAAMI Sleeves
Both the Premium and the Professional .223 Boresighters can be used for a variety of chamberings by fitting additional caliber-specific sleeves (sold separately). Each sleeve is precision-machined from brass to SAAMI specs. Available chamber sleeve calibers include:
An in-chamber bore-sighter is also useful when working with chronographs. The laser can quickly confirm that shots will pass through the correct measuring zone of the chronograph. For best chronograph results, with fewer errors, it is important that the bullets pass through the “sweet spot” of the chronograph. In a typical chronograph with V-type screens, that spot is 5-10″ directly above the light sensor.
With a PVM-21 chronograph, shown here, the “sweet spot” is in the middle between the left side/right side opposing infrared units. You can see the green laser easily on a piece of cardboard or paper. In our tests with rimfire ammo, actual bullet impact was within 1/2″ of the laser dot location. Using the laser bore-sighter, we were able to fine-tune shot placement to virtually eliminate errant readings with five different brands of chronographs. The laser IS a useful tool.
Other Types of In-Chamber Laser Bore-Sighters
In-chamber laser bore-sighters are also made by Aimshot, Firefield, and SightMark, and Sight-Rite in a variety of sizes. The bore-sighters sold by these companies are all less expensive than the LaserLyte/Cabela’s Premium or Pro model.
SightMark Laser Bore-Sighters
The SightMark line of laser bore-sighters is the most extensive we’ve found, with 20 different models for rifle, pistol and shotgun. Though priced inexpensively ($29.99 typical retail), the SightMark lasers seem to work reasonably well for the intended job. (See table below.)
Aimshot In-Chamber Bore-Sighters
Aimshot offers in-chamber bore-sighters for the .223 Rem, .204 Ruger, 30 Carbine, 17 HMR, and 9mm (pistol). In addition, there is a large selection of arbors (external sleeves) that allow Aimshot’s .223 unit ($41.00 street price) to fit many more chamberings. (See table below.)