The laser is powerful enough to see it in daylight
Shifting it around only amounts to a couple of millimeters difference at the target. The beauty of it is that it is easy to use and does a great job of getting your first shots near the center of your target without wasting a lot of time and ammo. Works really well if the end of the barrel is clean and square; all I have used this have worked well. Put a thin piece of paper between the magnet and the barrel to avoid scratching the magnet. I like it!
I have only used this once so far but it worked flawlessly. I used it on my Marlin 17v (with a newly mounted scope) at 100 yards.
Using a reflective target helps. At first I thought I had to have the centered exactly on the end of the barrel in order for it to work properly, but I soon realized that it not make any real difference.I just sighted in two guns with this bore sight, and this sight makes it easy. The magnet is great and the laser is straight and from what I can tell, if it was rotated does not give a different target point. I bought one of these to install a new scope on my deer rifle and on an AR15 that I just recently built.
So far this is great. I have it on my rifle and it is bright and doesn't move. My only complaint is that it is larger than I originally thought ,about the size of a small flashlight. Not a big deal for me but keep that in mind if you are working with space issues.
Laser was easy to see at that range in the afternoon sun and once I had adjusted the windage and elevation so the laser was close to center on the target I removed it from my rifle and sent two rounds downrange. Both rounds were on the target approx. three inches high from the bullseye.
I am a retired Naval Intelligence Officer who served in the Nam Conflict (1970). I own and have had my share of weapons in my years of experience. The is like nothing that I have seen before. It is true to your weapons barrel in no matter what distance you are calibrating your sights. The laser is powerful enough to see it in daylight with a 10 x 30 Monocular. The greatest attribute is that you only need this one slighter to calibrate any weapon that you own. In addition, the quality of the magnet is over kill for attaching it to the barrel.