Whatever works.
Here's a trick for AR's, Bill.
I have about 20 ft. from my workbench in loading room to the living room wall. Made this bore sighting target for various heights above bore rifles. The AR's usually around 2-2 1/4 above bore, so use center hash, bolt guns usually 1 3/4 use bottom one.
Center "target" in bore and adjust elevation to corresponding horizontal line on target will get you on paper.
Disregard the extra target below as it is a special check for my pet bolt gun drawn up after rifle was zeroed on range to duplicate sight picture. As you can see, bore sighting is not zeroing, but gets you on paper. 
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