He is a big difference between the younger folk and us old geasers.
You all are into buying, we all are into making. I do not know how much that gizmo costs, but I am about to skool you on how to bore sight for about a quarter.
Here are what you need. If you are a home owner u already have this stuff.
A step ladder, a pillow, a wall and a target (your 25 cent to have one copied at kinkcos.
I use my garage door so i can do it inside, but any wall will do.
Paste your target at 5 feet on onto the wall.
Back up 25 feet, and set up the ladder so that the rungs face your target.
depending on which type of firearm you are using, this step may very and some semi-autos you have to use a mirror to see down the chamber.
Lets pretend its a scoped bolt gun or scoped AR. Since you can remove the bolt and see down the barrel.
Set you pillow on two of the rungs latterly so that it is facing your target.
Next stuff your firearm on top of the pillow facing the target.
With your good eye, sight thru the chamber and line up the center of the bore with the center of the target. coloring the center one inch helps see it, dont forget to give the kid back their crayon.
Now that you are all set up, raise your head sight thought the scope and crank on the adjusters until your crosshairs are dead center left and right, and 1/4 to 1/2 in above dead center.
Take your rifle out to the range and you will find you are zeroed at 25 yards, and will have to adjust for vertical shot placement.
Dang you learned something today.