Why the story? I think there is a lot of value in devices like this. Clearly, you would not sight in your rifle using just one of these. But if you drop, knock, or whatever your rifle, it would give you a little peace of mind knowing that it is not significantly off. After we sighted in my son's rifle, both the laser and scope were fairly close.
Since 243, 308 and 7mm-08 calibers are all covered by the same size boresighter, I decided I would use this to help me boresight my new FNAR rifle with the Zeiss Conquest 4.5-14x50mm scope.
I'm not sure about other boresighters since this is the only one I have owned, but one thing I did not like about this one is that after you put in the batteries, it is on until you take them out. Really this is not a big deal while doing a quick check around the house, but it is not something you want to do over a bunch of leaves or grass while out in the field in case you drop one of the three batteries while trying to get them in place and in the right direction.
After putting the boresighter in my rifle, I set the scope crosshairs to be on the laser dot at about 36 yards. 36 yards is approximately where my first zero point shoudl be and this should get me on the paper (and hopefully very close). It also happens to be the distance from my side door to my brick mail box. I put the rifle on my roll around trash can, shimmed up the pistol grip with some Tupperware (had to run in twice to find the right height), and was able to take this shot with my camera while looking through the scope. The photo is a little grainy because I had to crank up my ISO settings on the camera.
Afterwards, I set my target turrets to their zero positions.
I finally made it to the range. The photo below shows how close the boresighter got me to being on zero. The two holes on the card board to the left are my first two shots at 50 yards. Cut me some slack on how far appart they were from each other. It was a very windy day and my target was jumping around big time. It didn't look too bad on elevation, but the windage was between 6" to 7" left. I was a little surprised it was not closer.
Now it was time to examine the boresighter a little closer. I took the bolt out of my Remington Model 788 243 rifle so I could rotate the boresighter easliy and then marked a 12 o'clock position on the boresighter with a pen. I placed the rifle on a bipod and let the laser dot project on the wall 27' away. I then taped a sheet of paper on the wall and marked the center of the dot. Next I rotated the laser to 3, 6, 9 and 12 o'clock positions two more times and marked the center of the laser dot each time. This ended up showing a maximum circular-ish scatter of dots of 0.72". Also I noticed that the laser dot itself was not keeping a nice round shape. Clearly, the 0.72" difference in 27' can be as much as 4" off at 50 yards. Also, when you consider that the laser beam was hitting the edge of the barrel in some positions and causing the non-round dot, there must be an alignment issue with the boresighter. The next photo shows my crude data.
I also tried to show the difference at the end of the barrel with this photo below. I placed a sheet of paper over the barrel and you can see the outline of the barrel and the laser dot. Clearly, the dot is not in the center.
Now that I know this, what am I going to do about it? I'm going to have to think on this.