Pre-sighting
You will save a significant amount of expense and frustration by pre-sighting the scope to the rifle before you take it out for zeroing.

Collimating, the most accurate and simple technique for pre-sighting, is the system most often used by gunsmiths. It can be done quickly in the shop before leaving for the range.

If a collimator is not available, you can still do a good job of pre-sighting by a method known as " bore-sighting". At the range, set the scoped rifle up on sandbags or other steady rest and place a target at 100 yards. With the bolt removed, look through the chamber and move around the bore until you can see the bulls eye centered in the bore.

Without moving the rifle from this position, glance through the scope and note where the reticle is positioned on the target. If the scope reticle is not closely aligned to target center, you need to adjust the base mounting screws. Do not use the scope windage and elevation adjustments for these pre-sighting adjustments or you will run out of adjustment for final zeroing.

All ABO (USA) serviced scopes are tested to be certain that they provide maximum internal adjustment range. After testing, the reticle is centered in the scope optically and mechanically. However, variations in rifle receiver dimension, mounting holes drilled out of alignment with the receiver or barrels threaded into the receiver at an angle will cause initial scope misalignment.

Therefore, it is important to make all major bore sighting adjustments using the mount adjustment screws. Make only final adjustments using the scope's internal windage and elevation screws. This will prevent running out of internal adjustments.


Note:
There is no acceptable way to increase elevation adjustments except to shim. Shim stock .010" thick, placed under the rear of the mount base will raise the point of impact about 7". To lower the point of impact, place the shim stock under the front end of the base.

Zeroing a scope
The range at which a scope should be zeroed is a matter of personal judgment. If you anticipate using the scope at distances of 100 yards or less, naturally a 100 yard zero is appropriate. Mid-range trajectory would be about 1" above the line of sight and you could hold directly on target all the way out to about 125 yards. If the anticipated hunting distances are 200 yards or more, you should zero your rifle at the longer ranges. The MRT for a rifle zeroed at 200 yards is minimal for most cartridges (usually about 1.5" to 2") and you can hold directly on target for ranges out to slightly more than 200 yards.

If a 200-yard range is not readily available, you can obtain a satisfactory 200-yard zero on a 100-yard range by zeroing about 1.5" high.

A good rest, such as sandbags or steady rest to reduce sighting errors, will help you hold more steadily on target. Rest the forearm, not the barrel, on the rest. If possible, zero in a no-wind condition to establish a standard zero. If you must zero in a wind, make a note of the amount of drift attributable to wind effect and when finally zeroed, make a compensating adjustment to leave the scope at standard (no-wind) zero. For example: a 15MPH wind from the right at the 3 o'clock position will normally drift a .30-06 factory bullet about 1.5" to the left. When you have finished zeroing in a 15MPH wind, simply adjust the Windage knob 1.5" to the left. This will result in standard no-wind zero.

The first time about 25 yards out from the muzzle. You can utilize this fact by firing your first zero shot at 25 yards target. If the first shot prints very close to the center of the bulls eye at this range, you can be confident that it will print on paper at 100 yards. If there is a significant error at 25 yards, make compensating changes to bring the point of impact to zero. Since the distance is only 1/4 of the 100 yard final zero distance, you will need to make 4 times as much adjustment as you would at 100 yards.

For final zero, move the target to 100 yards (assuming this to be the desired zero distance) and fire at least 3 shots to establish a pattern. Using the center of this group as a reference, make any necessary adjustments to move the point of impact to center. You should fire another group of 3 shots to verify that this adjustment was correct. Do not trust a one-shot zero as accurate.

Note:
For maximum precision, allow the barrel to cool between shots. A warm or hot barrel shoots differently than a cold one. In the field a shot taken at game is usually from a cold barrel, so you will want to have your gun zeroed when cold.
Making windage and elevation adjustments
The elevation knob is marked "UP" with an arrow indicating the direction to turn the knob to move the point of impact up on the target. The windage knob is marked "R" with a similar arrow indicating the direction to move point of impact to the right.

Many scopes have a graduated scale around the adjustment knob which increments representing a certain amount of point of impact movement on the target. The most common increment is 1/4 minute of angle which means one click or per increment adjustment moves the point of impact 1/4" at 100 yards.

Per increment 25 50 100 200 300 400 500
1/2 MOA 1/8 1/4 1/2 1 1 1/2 2 2 1/2
1/4 MOA 1/16 1/8 1/4 1/2 3/4 1 1 1/4
1/8 MOA 1/32 1/16 1/8 1/4 3/8 1/2 5/8
Unit Inch


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ParallaxHow To Set Parallax And Objective Focus
MountingHow To Set Mounting System
Sight InHow To Sight In (Zeroing) Scope

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