KEV,
Get a
laser boresight if you can ... It will put you on paper very quickly.
I use mine at dawn or dusk when it is easier to see the laser and still provide enough light to see the crosshairs of a scope.
Dial in at a known range, then sandbag it at a range, or just use a bipod if equipped ... The key is stability as you hold the crosshairs on target ... Three shots then adjust accordingly.
I use this method and can usually be nailing the limits of the ammo with very few shots taken.
FWIW: This is the one I use -
Cabela's Laser Boresighter
Best of luck!!