The object here is to not assume that everyone knows how to sight
in their rifle. There are many new hunters and shooters every day. When we go to the rifle
range, we all want to be able to at least hit the paper target. Before you do this
you should understand how a scope functions.
Know
Your Scope
Riflescopes have become far more
sophisticated over the years, but the four most basic parts have remained the same.
Working from front to back they are:
- The objective
lens (or front lens) is critical to a superior sight picture.
- The internal
erector lenses which right the image.
- The reticle,
often referred to as the crosshair, provides the aiming point.
- The ocular lens
(or eyepiece lens) works with the other lenses to magnify the image, provide correct eye
relief, and make diopter corrections.
How Scopes
Work.
As light passes through and beyond the
objective lens, the resulting upside down image is sent to the internal lenses. Known as
erector lenses, these internal lenses return the image to a right-side-up position.
Finally, the ocular lens makes a final enlargement of that image and sends it on to your
eye.
How to Install the Scope
(Please read the entire
handbook that comes with your scope before mounting your scope.)
Caution: Make sure your gun is unloaded before
mounting your scope!
The Lower
the Scope, the Better.
A scope mounted close to
the rifle ensures proper cheek weld on the stock for a stable firing position and allows
for rapid target acquisition. Use the lowest possible ring height. No specific
clearance is required, but the scope must clear the bolt handle, hammer (on lever actions
and handguns), sights, and barrel.
When installed, be sure that your
scope does not interfere with firearm operation and does not contact anything except the
mount rings.
Installing
the Base, Rings, and Scope.
Please refer to the instructions included with the base and rings for their
proper installation on the firearm.
Establishing
Eye Relief on Rifles and Shotguns.
Because of the
safety considerations associated with proper eye relief, it is
recommended that you mount your scope as far forward as possible. Beyond that, follow
these steps:
- With the scope as
far forward in the mounts as possible, hold the rifle in your normal shooting position.
(Variable power scopes should be set at the highest magnification for this process.)
- Slowly move the
scope to the rear just until you can see a full field-of-view.
- Position your scope
here for maximum eye relief.
- Proceed to
COMPLETING THE INSTALLATION.
To confirm that
your scope is mounted in the best possible position, try assuming various positions:
kneeling, seated, prone, and aiming both uphill and downhill. Remember that aiming uphill
typically reduces eye relief.
If a scope is
mounted too far to the rear, the eyepiece can injure the shooters brow. Shooting at
an uphill angle also increases this hazard because it shortens the distance between the
brow and the rear of the scope. Therefore, when mounting your scope, position it as
far forward in the mounts as possible to take full advantage of the scopes
eye relief.
Establishing
Eye Relief on Handgun Scopes.
Since handguns are
typically fired from an arms-extended position, eye relief is less of a safety issue than
with riflescopes. However, its still important to get the eye relief right for you.
1. Holding the handgun in your normal shooting stance, position the scope in the rings to
achieve a full field-of-view.
2. Proceed to COMPLETING THE INSTALLATION.
The eye relief of handgun scopes is more forgiving than that of rifle scopes.
Nevertheless, it is important that the eye relief is compatible with your shooting style.
Unlike riflescopes, adjustments to the eyepiece in handgun scopes affect the eye relief as
well as the reticle focus. Turning the eyepiece clockwise increases eye relief and turning
it counterclockwise decreases it.
Completing
the Installation.
- Without disturbing
the optimal eye relief position, rotate the scope until the elevation adjustment dial is
at the top of the scope.
- From a firing
position, check to be sure that the vertical hair of the reticle aligns with the vertical
axis of the firearm. Misalignment will not affect accuracy at moderate distances but it
can diminish long range accuracy.
- When you are
satisfied, tighten the ring screws evenly and securely.
Focusing the reticle.
Secure
the scope and firearm in a firm rest. Point the scope at a light colored background
object. With the scope approximately four inches from your eye the reticle should appear
sharp and crisp; if it does not, it is necessary to adjust the focus by means of the
eyepiece.
If your scope is
one with an eyepiece that has a lock ring, follow these simple steps:
- Grasp the eyepiece with your hand and
back it away from the lock ring. Once the lock ring is free from the eyepiece, turn it
clockwise away from the eyepiece to keep it out of the way during the adjustment.
- If you tend to hold things away from
yourself to see them clearly (you are farsighted) turn the eyepiece counterclockwise by
three or four turns. If you hold things close to yourself to see them clearly (you are
nearsighted) turn the eyepiece clockwise by three or four turns.
- Looking through the scope when pointed
at the sky, take a few quick glances at the reticle. The focus of the reticle should be
noticeably different from when you started. Continue this process until the reticle
appears clear and sharp.
- When you are satisfied with the
image of the reticle, turn the lock ring so that it rests firmly against the eyepiece.
If your scope is one with a
fast-focus eyepiece, follow these simple steps:
- All adjustment is made
with the eyepiece.
- Look through the
scope with quick glances while focusing the reticle image. If you tend to hold things away
from yourself to see them clearly (far-sighted) turn the eyepiece ring counterclockwise
until the reticle is clear and sharp. If you hold them close to yourself to see them
clearly (near-sighted) turn the eyepiece ring clockwise until the reticle is sharp and
clear.
If your eyesight
changes, readjust the eyepiece. As we age, eyesight normally changes. You may want to
check the sharpness of the reticle on your scope every few years to ensure it is still
adjusted correctly for your eye.
The primary function of a
scope is to aim the firearm. Never use the scope as a substitute for binoculars. Never
watch another person through the scope.
How
to Sight In
Using a Bore-Sighting Collimator.
To save time and ammunition, start out in your
shop or gun room with a bore-sighting collimator (a spud and an optical assembly) to
get on the paper. Remember that adjustments made during bore-sighting will
appear to move in the opposite direction than that indicated by the adjustment dial.
- Assemble the
collimator with the correct spud and insert it into the barrel.
- Look through the
scope. Note that the collimator displays a crosshair that is at 45º to the scopes
reticle. The center of the scope reticle is normally some distance away from the center of
the boresight reticle. This shows the scopes line of sight relative to the axis of
the bore.
- Begin with the
windage adjustment. (Remember, when possible, it is better to make the initial windage
adjustments to the mount base before using the scopes windage adjustment.) Turn the
windage adjustment until the vertical crosshair of the scope covers the center of the
collimator crosshair.
- Adjust the elevation
until the horizontal crosshair of the scope covers the center of the collimator crosshair.
With that, the scope should align with the axis of the bore.
- Remove the
collimator spud from the barrel.
Bore-sighting
alone is not sufficient to sight-in a scope. You must make final adjustments by shooting
the firearm using the same ammunition you use in the field.
Traditional
Bore-Sighting (Bolt Actions)
Preliminary
sighting-in can also be accomplished by bore-sighting at the firing range using a target
from 20 to 50 yards away.
- Position the
firearm on the bench, using sandbags to steady the firearm.
- Remove the bolt
from the firearm.
- Looking through
the bore itself, move the firearm to center the bulls eye of the target inside the
barrel.
- Hold the rifle
steady. With the bulls eye centered when viewed through the bore, make windage and
elevation adjustments to the scope until the very center of the reticle is aligned with
the bulls eye of the target.
Bore-Sighting
Lever Actions
An
inexpensive device with a small mirror, which inserts into the chamber or rests on the
magazine follower to allow sighting down the barrel, is necessary for bore-sighting lever
action rifles.
The Final Step: Three-Shot Groups
Whichever
bore-sighting method youve used, the next steps are the same on the firing range. To
ensure reliable results, always fire from a rested position when performing these steps.
- Fire a shot or two.
- If you are several
inches off center, make an appropriate amount of adjustment to move the reticle to the
center of the target.
- Carefully fire a
three-shot group.
- Use the center of
that group as a reference point for the final adjustments to windage and elevation.
On the sample
target, the center of the group is two inches low and three inches right. Assuming
youre sighting-in at 100 yards, you should make a 2-MOA adjustment up, and a 3-MOA
adjustment left. Your next three-shot group should be very close to the center of the
target. To learn about making final adjustments, proceed to the upcoming section on
windage and elevation adjustments.
Making
Precise Windage and Elevation Adjustments
The style of elevation and windage
adjustments on scopes varies with specific models. If you are unsure of the value of
your scopes adjustment increments, follow these steps.
Determining the value of adjustment increments:
- Count the number of
hash marksfrom zero to and including that of the first numberon the dial.
- Divide the
first number on the dial by the number of hash marks counted. For example, divide 1 (the
first number on the dial to which you counted) by 4 (the number of hash marks counted) to
get .25 or 1/4.
The resulting
number is the value of each increment of adjustment in MOA. This method will work with
almost any adjustment dial. One MOA moves the point-of-impact at 100 yards by one
inch (at 100 meters, it moves 29mm).
The windage adjustment has arrows pointing at an L for left or an
R for right. The elevation adjustment has arrows pointing at a U
for up or at a D for down. All of these symbols refer to the direction that
the point-of-impact of the bullet is moved.
What You Should Know About Variable Power
Scopes
Variable power scopes allow you to
select from a range of magnifications to suit your particular rifle, cartridge, and
shooting needs.
All variable power
scopes have a power selector ring in front of the eyepiece assembly. Turn the ring to
align the number indicating the desired magnification with the dot on the body of the
scope.
Understanding Parallax
Parallax is the apparent movement of the target
relative to the reticle when you move your eye away from the center point of the eyepiece.
It occurs when the target does not fall on the same optical plane as the reticle.
Maximum parallax occurs when your eye is at the very edge of the exit pupil.
At short distances, the parallax effect does not affect accuracy. It is also good to
remember that, as long as you are sighting straight through the middle of the scope, or
close to it, parallax will have virtually no effect on accuracy in a hunting situation.
Scope Maintenance
Lenses
Scope lenses are coated
to reduce light reflections and light scattering thus increasing light transmission
through the scope. They should be cleaned as carefully as you would a camera lens.
Use a standard lens brush to remove dust and then pure alcohol, high-grade glass cleaner,
or pure water on a cotton swab to clean the lens.
Windage /
Elevation Adjustments
These adjustments are
almost always permanently lubricated. There is no need to lubricate them. Keep the turret
caps on, except when adjusting, to keep out dust and dirt.
Seals
Most scopes are sealed
from within by several methods, including O-rings. All seals are permanent and require no
maintenance.
Scope
Exterior
No maintenance of any kind is required;
simply wipe off any dirt or fingerprints that accumulate with a clean, dry cloth.
Trouble Shooting Tips
Before you
ship a scope back to the manufacturer for service or repair, please check the
following items to make sure that the problem is really with the scope and not the rifle
or mount system.
- Check the mount.
Make sure the scope is mounted securely to the rifle. Try, with bare hands only, to twist
the scope in the rings or see if anything moves when you jiggle it. If there is any
movement, retighten the mounting system according to mounting instructions.
- Make sure the action
of your rifle is properly bedded in the stock, and that all receiver screws are tight and
have been tightened in the sequence recommended by the manufacturer. A loosely fitted
stock can cause changes to the point-of-impact.
- When test firing a
rifle to check the point-of-impact relative to windage and elevation adjustments, be sure
to fire from a solid bench with sandbags supporting the forearm and buttstock.
- Be sure to use
factory-loaded ammunition of the same bullet type, weight, and preferably, lot number. If
one type of ammunition does not shoot well, try another brand or bullet weight.
Be certain that
both the barrel and chamber are clean. Heavy factory grease on a new rifle and copper
fouling on an older one can diminish the accuracy of the firearm.