Shotgun Boresights

Personally, these "in the bore" sights are the only kind I'll use when possible because they are just so easy. I got this to sight in my Bushnell Trophy TRS-25 1xRed Dot Sight Riflescope and it works great. All you do is open it up, put in the little batteries, and screw it shut. Once closed, the laser comes on. Then load it as you'd load a shotshell. Sight your stuff in, and cycle the action to eject it. There's no on-off switch but then there's no room. It actually sits in the gun where a round would normally. As such there isn't any fiddling, it is accurate right off. Only two downsides, but neither are anything that can be fixed in something of this design: 1) Short battery. Laser diodes chew up battery and these ones are small. So use it, and then take it out. Don't leave it on and play with it unless you like buying lots of batteries. This is just a consequence of the small size. You can't drop AAs in something that small, so it has very little battery power. 30 minutes or so, an hour at most. 2) Not visible in bright sunlight. This is because higher class, more powerful, lasers require a key interlock according to the FDA and you couldn't have that on something that goes in the firearm. So it is as bright as you get from a red laser diode in that class. Don't worry, it is still perfectly visible indoors in regular light, you don't have to be in a darkened room or anything. However you aren't taking it to an outdoor range and making any use of it there. Personally I'd recommend only getting the "ammo sized" boresights for any caliber of gun that you can find them. Yes you do need one per caliber, but they are so much easier and less fiddly than the ones that screw in to the end of the barrel.

I have four of the Sightmark laser boresights - the 12 gauge, 9mm, 7.62x39mm, and .223. I had used a Bushnell laser boresight before getting this set of chamber loaded laser boresights. The Bushnell is the kind that you stick into the muzzle end of the gun, fitted with an arbor matched to the barrel size. The problem with this device was that the arbors never fit quite right - they were always either too tight or too loose, plus you had to try to seat the body of the boresight in the center of the opening of the barrel (or muzzle brake) in order to properly align the center axis of the boresight with the center axis of the barrel. This rarely if ever happened just right as the slightest tilt in the seating of this boresight in the barrel would take it off the center axis so that rotating the laser would cause the laser light to mark out a small circle that was several MOA in diameter rather than being dead centered. Ugh. Of course with these chamber loaded laser boresights, there is also the potential for the lasers to be mis-aligned off the center axis. Plus there is the potential for the boresight to not fit the chamber properly. The key is to find a brand that has a measure of quality control so that you aren't stuck with these problems. I read through a lot of reviews before deciding on Sightmark. It is definitely not the cheapest out there. There are so many different brands and generic versions of these chamber loaded laser boresights now that almost look alike, with many much cheaper than the Sightmark. However, it was clear from reading the reviews that as the prices went down, so did the quality control. Several of these cheaper brands came with complaints that the lasers were not aligned to the center axis (resulting in the laser painting a circle as it rotates in the chamber) or that they did not fit properly in the chambers and so would either get stuck or wiggle. I have this theory that the really cheap laser boresights must be factory seconds or some such. I considered the Osprey line with the adjustable arbors, which saves money by allowing you to use one laser bore sight for different calibers. But, the reviews indicated that hassling with arbors would have an effect on accuracy and reliability. I almost got the Firefield, which seemed to have a similar number of decent reviews. Ultimately I decided against it because the entire line is made of an aluminum shell, and I think the brass shell of the Sightmark will hold up better. It should be noted, however, that the 12 gauge Sitemark is made out of aluminum, unlike the others, and is only painted a brass color. The biggest complaint against all of these laser boresighters are the frequent DOA batteries and poor battery life. The Sightmarks all come with alkaline button cell batteries. The small caliber ones (9mm, 7.62mm, .223) come with two AG5 batteries while the 12 gauge came with three AG13 (LR44) batteries. To get you all confused, the printed information on the back of the packaging for the 7.62mm and .223 says you can use 3 AG3 batteries in place of the 2 AG5 batteries (since the AG3 is a thinner battery with the same 7.9mm diameter), while the printed info for the 12 gauge says you can use 2 AG5 or 3 AG13 batteries. This is flat out incorrect since 2 AG5 batteries are too small to fit into the 12 gauge Sightmark battery chamber. Confused? Go to wikipedia and look up the article "List of battery sizes". Scroll down to the section titled "Silver oxide and alkaline cells". The table lists all the different names for each battery, their dimensions, and their mAh power rating. Note how the silver oxide batteries contain 1-1/2 to two times as much energy as the alkaline batteries. So the key is to go out and get some silver oxide button batteries, size SG5 for the AG5 powered Sightmarks and SG13 for the AG13 powered lasers. And don't go to your nearest retail store, since that will cost you an arm and a leg. Google shop for these batteries online. I found two Made in China "brands" one called Vinnic and another by Chung Pak Battery Works which were pretty cheap. The names aren't important, since I'm sure they will change rapidly. Just remember to get some silver oxide batteries online at the same time you are getting these Sightmark bore sights. How well did these Sightmarks work? The very first time I used one (the 7.62x39mm), I plugged in the included AG5 alkaline batteries and the resulting laser light was exceedingly weak. My initial reaction was that this was a bad laser. Then I remembered the silver oxide batteries I had gotten. When I switched out the batteries, the laser suddenly glowed brightly. Later, when this set of silver batteries finally wore down, the laser light faded again. That's a sign to change batteries. The larger AG13 alkaline batteries for the 12gauge shotgun boresight worked reasonably well and are still working as of this writing. Not surprising, since these batteries pack a lot more energy than the small AG5 batteries. As many have noted, the Sightmarks do not have an on-off switch. Once the batteries are screwed in the laser light is on! This is just as well, since the bore sights have to flush fit inside the chamber of the barrel and endure having the bolt and firing pin slammed into them. But you do have to have a plan of action ready so as to not run down your batteries. With one pair of SG5 silver oxide batteries, I was able to adjust the sights for about four guns, each taking about 5-10 minutes. So I am guesstimating a battery life of about 30 minutes with a fresh pair of SG5 silver batteries (the Sightmark packaging claims up to an hour of battery life - hah!). All of the Sightmarks have fit in well, none have gotten stuck (so far), and none have had off-center lasers. These chamber loaded Sightmark boresighters make it easy to dial in a scope, and for fixed sights, they help confirm the aim points. They are much better than the muzzle loaded bore sights, although the total cost is a lot more since they are ammo caliber specific.

Not only are these more precise as they're loaded into the chamber, they're very accurate as the red dot position does not deviate when the "shell" is rolled 180 degrees in the chamber. On a badly calibrated unit, this would result in the red dot drifting to the other side of the scope. but in this case it remains perfectly still. The carry case is a nice addition as well. Only downside, no off button, you have to remove the batteries. But, just like those lighted Christmas decorations with preloaded batteries, you can just insert a small piece of plastic between the last cell's positive side, and the screw on cap to make your own manual off switch.

I own several different laser bore sights by Sightmark, in a number of different calibers. I also have one of their universal laser bore sights. I've found all of their products to work quite well so far. I've found these in the chamber type of laser bore sights to work much better than the universal types which hang out from the muzzle. The machining on these in the chamber types by Sightmark is quite good. With the firearm firmly mounted in a heavy bench rest, I've rotated the sight to several positions in the chamber and seen very little change in the point of the dot even at 100 yards, which indicated to me not only a very good machining, but also a very good adjustment of the laser within the brass body. One thing to bear in mind with these sights are that while they do feature a rim like a standard cartridge, the sight is not meant to be removed from the chamber by means of the extractor and bolt. While you will get best results by gently letting the bolt close and push the sight snugly into the chamber, the sight will not simply fall out upon opening the bolt and again, it is not meant to be extracted like a standard cartridge. to remove it is best to open the bolt and keep it open while using a cleaning rod from the muzzle end to gently push the sight out from the chamber. While very well made and adjusted, these devices still have very slight variations from true center, which becomes more noticeable with distance as does the increase in the size of the dot. Yes, it is a laser but it is a laser diode, not a high end gas or sapphire rod laser, so the coherence of the beam is not 100% and the diameter will increase with distance. That isn't a negative though as it helps you to see the dot at distance with the naked eye. Try seeing the period of a sentence on a newspaper page 25 yards away with the naked eye and you'll get what I mean. Even with the increasing dot size at distance and a good spotting scope though it is best to use the laser bore sight in less than full daylight light levels. These laser bore sights are truly ideal for a shotgun though, as they give outstanding results at distances under 50 yards. With a 12 gauge shotgun you really aren't likely to be trying to hit dead center of a bullseye as you would with a rifle or pistol, let alone would you be doing so for a distance of 100 yards. If you are using this to set ghost ring sights, reflex/holographic or laser sights for use on a defensive shotgun however, the distance required is considerably less and the results of using this bore sight will be as close to perfect as you should want. Due to its size this laser bore sight probably could have used a single CR123 battery rather than three small AG13/357A, or LR 44 batteries that it requires, but it's not likely to be used often enough for that to be an issue. It also would be nice to have an on/off switch rather than having to remove the batteries, but again due to infrequent use it is not really much of an issue. It could have used a green laser which would have greater visibility at long distance or in full daylight, but for a shotgun the distance isn't an issue and a green laser would have driven the cost up to more than double what it is.

I already own two other caliber Sightmark laser bore sights, so it was not a hard decision to purchase this one. Although some review made various complaints...E.g. "It is not accurate...I rotate it and it does not stay on point" - not true with any of my Sightmarks. "The battery runs out.." Hello! Its not a laser sight...use and stow. "It jams when I load it"...well, first, WHY would anyone load it like a load?? Place it in the bore...it's a piece of electronics, not ammo! "I can't use it in day light". Ug, I have a Mossberg 500 JIC, made for CQC or home defense. With that, I only need 25 yards. I had NO problem sighting it in, upon my drive way, at a white garage door. Anyways, I'll put to rest all three of those complaints (at least in my controlled tests)...I kept it on way more that I should, for the purpose of OVERUSING it (I needed to sight in my holographic red dot and laser)...there was NO noticable drop in battery life or laser output. I then put the unit in the chamber, secured the gun and rotated the sight 360 degrees (twice)...no change in placement of dot!. I then chamber the unit 12 times in a row like a shell (good hard slams), no jams or failure...even rechecked the alignment again. Dead on. Last I stood the full 150 feet of my drive way in daylight, and saw the dot! In close, everyone do/buy what you want, but Sightmark is the ONLY laser bore light I will ever own. P.S., for those that want an on/off switch and don't like twisting the cap or removing the batteries for storage... "oh please....I won't even comment on that". This is NOT a toy. I am not knocking anyones past experience. This is only mine...for what it is worth.

Purchased this to help sight-in my 12ga shotgun when using slugs. My first goal was a 50yard zero and figured I could save some ammo and shoulder abuse by using a bore laser to get within an inch or two of the actual point of aim using my sights. WRONG. I also thought that I could use it to align a laser sight with the point of aim. WRONG again. The main problem is that at 50 yards, the laser dot is very diffuse and at least twice the size of the actual bullseye. I'd say the dot ended up being 3-4 inches in diameter. So in reality, the dot was actually less precise than looking through the iron sights alone. If you are already hitting anywhere on the target at 25yards, then don't even bother with this bore laser. If the problems stopped there, I would have given it 3 stars. However, it went down to 1 star because the laser is actually very very weak. I changed to fresh batteries (twice actually), thinking that maybe the batteries were weak. In an overcast afternoon I could not see the laser even at 25 yards until I put a piece of aluminum foil over the target. My vision is 20/20. Still, it was so faint that I couldn't see it while looking through my sights, instead, I had to completely lift my head and look hard for it. At 50 yards, it was simply not visible until the sun was nearly completely set, even on this overcast day. Ended up starting over, without the bore laser. After 20 minutes and going through about 15 slugs to dial in the sights using the traditional method, my Benelli M2 is now shooting rifled slugs with 1-2 inch groups at 50yards, and 4 inch groups at 100yards. Overall, I would not recommend this to anyone. It simply isn't worth the time, money, effort, or aggravation. You would be better off spending the money on the ammo and doing a traditional sighting-in process. I'll be posting this for sale in the Amazon used products section.

I bought this last fall to help sight in the rifled barrel on my 12ga. I tested it quick after I took it out of the box and the laser lit up so I packed it into my gear bag and headed out to the range. While I was trying to sight in my gun I kept having trouble with the laser turning off. I'd tighten the cap to turn on the laser, then I'd put it into the chamber and the laser would turn off. I dismissed it as bad batteries and sighted in the gun without the boresight. I put brand new batteries in the boresight this fall and the laser lit right up. Put it in the chamber and the laser turned off. Checked the boresight to make sure the cap was on tight, still no laser. Shook it a little and the laser turned on. After removing and reinstalling the batteries several times, the laser still shuts off at random. Eventually I managed to get it in the gun with the laser on but using this boresight has been frustrating at best. Chambering the boresight is more than enough jostling to cause the laser to switch on/off. Sightmark's warranty backs these products for three years, however according to their website, it is "only valid if the product is registered within 30 days after the product has been purchased". Hopefully I registered this when I bought it! When I called Sightmark's technical support group, the gentleman I spoke with was very friendly but as I expected, he told me that I'd need to send the unit in for repairs. Pros: + Feels sturdy and generally well built + Fits snugly into the bore + Laser aims true at 50 yards Cons: - Even with new batteries, the laser can be difficult to see in full daylight - The unit I received seems to have some sort of defect which causes the laser to shut off at random - There are no markings on or in the boresight indicating the size of batteries or which direction they are to be installed (this is fairly minor)

Great product