Re: sighting in a .243
Standard calibers I like to zero for 200, making 300 yard shots easy without calculations. I start by taking the scope and turn both dials through the full range of adjustment counting the clicks, adjust them back half the counts to center the adjustment range.
Then go to the method 410er mentioned. At 25 yd with gun solid in position, bolt removed, perfectly center the bullseye in the bore. Look at how it looks through the scope, if it is off more than just a little in L-R and the scope base is adjustable, center the scope L-R using the base adjustments. After this or if there is no base adjust, adjust the crosshairs to about 1/2" high on the bull. This will put bullet impact about 1/2" low at 25 yd when aiming at center. With most scope setups and flattish standard calibers this will put you around 1.5" high at 100, real close to zero at 200, and on hair at 300.
I fine tune then for zero at preferably 200, if not then high at 100 using a ballistics table for the correct amount required for the 200 zero.
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