I bought one of these a few months ago, and found that it was not up to the standard that I had come to expect of Bushnell products. As a bore sighter it was not very accorate, and I would go so far to say it was more of a bore aliner to get you on the target, but not to accorately set up your scope without shooting. You can test for alinement by sticking the sighter in a cordless driil and spinning it slowly. If you get a circle on the wall you know the sighter is out. What you are after is a single dot. You can improve the sighter by putting it in a lathe and using a dial gauge to centre it, but it is a right work up....Bushell have brought out a new unit where you rotate the front of the laser to turn it on/off. It has four grub screws around the front, bot mine were deformed and useless for adjustment of the laser. I think you have to ask yourself is this worth the trouble. I would say that there is nothing wrong with the idea but the engineering quality lets it down.