When a Tasco rifle-scope is first mounted it needs to be adjusted by sighting-in, the method of aligning a rifle-scope. Because no two guns will shoot exactly alike, and no two brands of ammunition will fire exactly alike, several brands of ammo need to be tested while sighting-in to get the best accuracy from your rifle. A Tasco scope is a high-quality instrument, and following the proper sighting-in procedure will produce the highest accuracy possible from your hunting rifle.
Set up a paper target 100-yards away. Support the rifle on a gun rest and attach the magnetic bore sighter on the end of the barrel with the scope accessory lined up with the rifle-scope. Look through the scope and align the crosshairs with the cross marked on the grid of the bore sighter. Adjust the bore sighter until the crosshairs meet precisely. Use any tools included with your model of scope to make the adjustments, and follow the instructions for your particular scope model. Remove the magnetic bore sighter.
Load one round of the first brand of ammo into the rifle and attempt to hit the bull's-eye. Wear eye and ear protection. Look through your binoculars to see if the round has landed anywhere on the target. If the round has not landed on the target, move it 25-yards closer and try again. Continue moving the target up in 25-yard increments until the round hits. You will not know which direction to adjust the scope if there is no mark on the target to guide you. If the round is too far left, adjust the scope to the right using the tools and following the instructions included with your scope model, and try again from 100 yards.
Aim for the bull's-eye and fire three rounds of the first brand of ammo at a new target. Mark the grouping of hits with a marker, then fire three rounds of the second brand of ammo. Mark the grouping of the second brand, and repeat this process for the third brand of ammo. Determine which brand of ammo got closest to the bull's-eye, which grouping of shots were closest together and which group was the most on-target.
Adjust the elevation on your scope so the crosshairs hit about 3 inches above the bull's-eye, then fire three rounds using the brand you determined best from Step 3. Use your binoculars to see if you hit 3 inches above the bull's-eye as intended, and make the necessary adjustments on your scope until you do. This is actually just a minuscule adjustment that will help compensate for shots farther away than 100 yards, yet will not interfere with targets that are dead-on within 100-yards.
Mount the magnetic bore sighter with the scope accessory lined up with the scope. Draw a diagram on a separate sheet of paper where the scope crosshairs are in relationship to the grid on the bore sighter. Use this diagram as a quick reference if your scope is ever accidentally knocked out of alignment in the field. This will help keep your shooting reasonably accurate until you can sight-in the scope again later.
Adjust the eye relief -- the distance between the eyepiece of the scope and your eye -- to avoid injury. This is especially important on rifles with heavy recoil.
Always observe firearm safety and leave your rifle unloaded until you are ready to fire a round.
Tips and warnings
- Adjust the eye relief -- the distance between the eyepiece of the scope and your eye -- to avoid injury. This is especially important on rifles with heavy recoil.
- Always observe firearm safety and leave your rifle unloaded until you are ready to fire a round.