i've had one and went back to the bushenll optical- first, you need a MINIMUM of 25 feet of clear throw - then, you can't see the ones i've tried in daylight( rec-t-fire) and the batteries were somewhat unique- with the bushnell, it's a matter of sticking the spud in the barrel , tighten it up, and then adjust- then REMOVE THE SPUD- there's a few examples on here of folks that FAILED to do that- have one again- NOT ON YOUR LIFE
the only time you need a bore sighter of any kind is when you're using a pump, lever, or semi- with the bolt, you just pull the bolt, and look through the bore, and set the scope and the bore so there's coincidence-
remember- the bore sighter will ONLY GET YOU ON THE PAPER- the FINE TUNING has to be done at the range and with the ammo you hunt with