Leupold RX Series Operating Instructions Manual page 5

FUNCTION 12: dECLINATION
ANGLE INPUT (RX-IV ONLY)
This mode allows the user to manually
set the declination angle, correcting for
deviation between magnetic North and
true North. declination angle for your area
can be found on the corner of any USGS
topography map or on several Internet sites (for example, go to:
www.ngdc.noaa.gov/seg/geomag/jsp/declination.jsp).
To set the declination, scroll through the Quick Set Rotary Menu
until "dEC" is flashing, then press SET. The angle will begin at 0˚ and
increase each time the SET button is depressed. You can hold down
the SET button and it will progress up at a slow rate. For negative
numbers, progress all of the way up to +30°. The next press of SET
will start the numbers at -30° and continue to progress in a positive
direction. Stop at the correct angle. Press MOdE to move to the next
mode in the Quick Set Rotary Menu, or wait for the power to "time
out" to save the declination angle setting.
NOTE: Pressing SeT continues to run through these settings until you
press MOde to move on.
NOTE: Magnetic fields are constantly shifting on the earth so
declination angle may need to be reset every couple of years for
maximum accuracy.
FUNCTION 13: TRUE BALLISTIC RANGE
TBR calculates the equivalent horizontal
range (level fire range) from which
you can determine the correct aim for
the conditions. For example, if you are
shooting a .270 caliber, 130 grain
(8.4 gram) bullet at 3,050 feet per second
(930 meters per second) up a 30° incline at
400 yards (366 meters), direct line of sight, the TBR output will
be 364 yards (333 meters). State-of-the-art processing algorithms,
developed by the same engineers who developed Sierra Infinity
Exterior Ballistics Software and who developed ballistics algorithms for
many space vehicles over the last 40 years, determine the True Ballistic
Range with incredible accuracy, eliminating potential errors that could
cause you to miscalculate your aiming point. The first step in correctly
using TBR is to Practice, Practice, Practice. Anytime you handle a
firearm or bow, you are ultimately responsible for your projectile.
The inclinometer output is shown below the LOS output or thermometer,
whichever is enabled. The inclinometer output will be disabled when
TBR is turned off.
For rifle users, adjustment or holdover information can also be
displayed. The available settings are as follows: MOA displays the
minute of angle correction, hOLd displays the inches or centimeters
to holdover the intended point of impact, and BAS outputs the
equivalent range to use with Leupold's Ballistics Aiming System
reticles or the equivalent horizontal range. RX-IV Boone and
Crockett ™ edition users can also choose to have the appropriate
aim point for the Boone and Crockett reticle flash, showing exactly
which portion of the reticle to use. TBR for rifle settings is effective
to 800 yards (732 meters) for most cartridges.
For rifle users, TBR mode is comprised of three functions: hOLd,
MOA, and BAS. One of these modes must be selected. To select the
desired function, scroll through the Quick Set Rotary Menu until TBR
is reached (activate if necessary). While the TBR icon is highlighted,
pressing MOdE repeatedly will scroll through hOLd, MOA, and BAS
respectively; press SET when the desired function is displayed. This
will be displayed in the section above the reticle.
For information regarding BOW settings, please see page 5.
hOLd will display your holdover for that
target at that distance, which is based upon
the ballistics group and sight-in distance
you will choose in a later mode. The upper
digits display holdover measured in inches
if feet or yards is the chosen measurement
output. Centimeters of holdover will
be displayed if meters is the chosen
measurement output. Your hold will be
shown as "hI 999" or "LO 999" .
MOA Mode will show the minute of
angle adjustment for your target,
accounting for the True Ballistic Range.
The upper display will show MOA
adjustment as "UP 999" and "dn 999" .
BAS displays the equivalent horizontal
range. This is the range you will want to
use when shooting, rather than the line
of sight distance, which may contain gross
errors depending upon the shot angle.
Returns will be displayed with equivalent
horizontal range.
NOTE: True Ballistic Range is available only in the RX-II, RX-III, RX-IV,
and RX-IV Boone and Crockett models.
©
TBR (TRUE BALLISTIC RANGE
™
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4
): RIFLE
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