Bayattoo Bore Sight 9mm/.40 S&W/45ACP/223REM Laser Sight Red Dot Boresighter with 9pcs Batteries

The laser bore sight kit has worked very well. I had seen complaints about the lasers not being aligned, and I never experienced that issue. To test alignment, I placed each laser on the desk and rotated them around, holding position using a square I had clamped to the desk. They all maintained alignment, measured by the laser holding position on the ceiling. The only issue I noted was with my Holosun HE507C GR optic. While the lasers were visible through my 407C and Osight SE, it was very faint while looking through the 507C. I am not sure if there is an optic coating used on the 507C vs the others, but I had to turn down the brightness on the 507C in order to see the laser. Overall, I highly recommend this kit for anyone looking to initially sight in their pistol red dots.

Good quality and helpful tool

Would have given this five stars except for short battery life. But- batterys are cheap (and maybe just the battereries included with the unit are just old/weak?) ,commonly available . This device is a lot cheaper (ammo costs about 40 cents a shot nowadays) , and much faster than wasting range time on this extremly important task. Even if the battery life issue is not fixable with fresh battereries -I'd still rate these units very highly-they are so quick to use that you can just remove the batereries after the five min. or so to adjust sights. AND-works fine in .38 special/357 revolvers -leave the cylinder open -the bore sight will hang out the back -but the 9mm will fit into the barell and allow you to adjust sights on revolvers in those calibers. Final point: Boresighting fixed sights can be sobering -but better you know than you guess they got it right at the factory. (Wonder why spelling checker doesn't work -I sure need it ?)

I have found them to be very useful. They are not absolutely perfect BUT they are great to confirm sight adjustments before going to the shooting range and wasting expensive ammunition. Remember to remove batteries after use. These small batteries don’t have a long life and you won’t want them to corrode while in the bore sighters.

Seems accurate...but the batteries only lasted for one session Edit: updating because the seller reached out and offered to send batteries. Superb customer service. Again, laser worked exactly as needed and expected so the product itself worked fine. Batteries are some no name brand it seems so if you have the same experience, just buy some better batteries. 5/5 would purchase again if I need other calibers later

I purchased this product for all of its intended reasons, but my experience was simply disappointing and frustrating. The batteries are a pain, not just the instillation, but because there is no on/off switch. They also drain extremely quickly, so if you use these lasers for any decent amount of time, you have to have a battery stash on hand. That's more money spent and more trash produced. OK, so you know that going into this product and decide to purchase it anyway, like I did. Well, if the slide doesn't fully close as it didn't in my experience, then its 100% pointless. What makes these bullet casing lasers attractive is as long as they are true, being able to fully chamber them leaves zero question as to where your shots will land. Yes, its not exactly that simple, but its better than one of those lasers you stick in the end of your barrel as far as accuracy is concerned. However, since mine wouldn't chamber, the barrel laser ended up being a better choice for obvious reasons. Due to the lack of a power switch, the amount of batteries these eat, the lack of quality control (you can see what I am referencing in other people's reviews), and the gamble of "will this chamber", this product wasn't for me and I can not recommend it. Your experiences might be different. The one positive was the cost, as it was one of the lowest requested prices for this type of laser when I purchased it.

makes it easy to .sight in weapon.

The Good: Craftmanship is excellent, the red laser is bright. I will be using these as a training aid to visually show my students that the barrel is always pointed at something whether you intentionally aim or not. The Not-So-Good: These use hearing aid batteries with no On-Off switch. You put the batteries in, screw the end plate back on the assembly, and the device lights up - till you take the batteries out, or they go dead. These tiny hearing aid batteries are about 1/10 the capacity of a typical "Cat Laser Toy" so expect run times in the single digit minutes. The other big observation is that these lasers are both intended for simi-automatic (9mm and .45 ACP) which use an extractor clip/hook to pull the empty brass shell out of the barrel. The extractor will press against the side of this laser and cause the beam to end up somewhere off-center (maybe a little, maybe a lot). And if you think you can beat this issue by locking the slide open, remember most pistol actions drop/tilt the barrel whenever the slide is back. Good Luck, and please be safe.