I have a lazer bore sighter and it works fairly good, but I say "faily" good, because it's not as good as my method of bore sighting.
After I do my bore sighting, very seldom and I mean very seldom, that you every have to shoot over 3 shots to be dead on at 100 yards. Most of the time it only takes 2 shots. I have done several rifles that only required 1 shot.
I put a 3/4" orange dot on piece of white card board and draw the V & H lines through the dot. I place this target at 35 yrds and place my rifle is my cleaning cradle. I aligne the bore up with the dot, then do the adjusting of the scope. Double and thripple check your adjustments.
Believe me this works very good and the more you do it the better you will get. I just done a rifle for a friend of mine last fall and he was amazed, first shot was 1" high @ 100 and #2 shot same place, that was it, he never shot any more, it was right were he wanted.
I really regret buying my laser now, wasted $150, oh well.