Marmot sent me a tiny laser bore sighter the size of a .223/5.56mm cartidge. These shell type laser bore sighters are designed to fit inside your chamber just like a bullet and shine a laser down your bore to case a laser dot and provide a reference point for your gun’s sights or optics.

The laser bore sight kit comes in a plain black plastic case. Inside is the laser bore sight, 3 sets of 3x LR41 button batteries, and an instruction pamphlet which details how to insert the batteries which power the device. The instructions recommend removing the plastic sleeves around the the batteries but I’ve managed to fit them with sleeves, which helps keep the batteries in the correct orientation when inserting them into the cartridge.

At the range I manually inserted the cartridge into the chamber of my AR. The advantage of using these type of laser bore sighter instead of the muzzle inserted wand type, is that these caliber specific in-chamber bore sighters are more consistently aligned to your bore because they sit inside your chamber. The downside is that they only work in the gun they are chambered for and they generally have poorer battery life.

Because of their small size (literally the size of a spent cartridge shell), they are powered by small hearing-aid button batteries which don’t really have much energy capacity. Generally I’ve found these batteries to be only good for a 1-2 range visits and a few months later, I find them dead. So it’s a good idea to keep plenty of spares.

Testing it at the range, I could easily see the laser dot on my target at 25yrds. A green dot is much easier to visually see at long distance but it was a bit of a challenge to see this red laser at 50yrds. On a sunlit paper target it would be practically impossible. It is possible to see the dot from 100yrds through a magnified optic in well shaded conditions but this can prove quite frustrating in less than favorable conditions.

There is a significant safety advantage to using this type of laser bore sighter over a muzzle/wand type. The bore sighter must be ejected before loading a live bullet in the chamber. With muzzle types, there have been horror stories of some hapless users, forgetting to remove the wand bore sighter from their breach and firing a proofing round to catastrophic results.

In my testing, I was easily able to zero a new red dot using this bore sighter at 25yrds. Whilst sighting naked eye through the bore, I was nearly 8″ off from point of impact on target. Using this laser bore sight, I was slightly less than 2″ from the point of impact. So, I can say this tool was much more accurate than my eyes.

This kit has a street price under $15 at the time of this writing. Considering 5.56mm ammo costs over a $1.50 a round most places, this tool could quickly pay for itself when zeroing out your next rifle.

It is available through my Amazon Affiliate link: https://amzn.to/3lEEGAg
Use this Discount Code

Marmot 223 boresight 15% discount code: ZUC3SEQC