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Simply stated, the Bullet Comparator measures
loaded rounds…precisely!
Measuring cartridge lengths across the bullet tips is not a reliable (or
repeatable) method for measuring your loaded rounds. It is not
uncommon for variations of up to .025" to exist from one round to the
next when measured across the bullet tips. Bullet tips vary
considerably due to the way in which bullets are made. Our Bullet
Comparator solves that problem by measuring your rounds from a
reliable surface on the bullet – the ogive – to provide consistent,
precise measurements of your rounds. The Bullet Comparator is also
used by many shooters to check uniformity of bullets – from base to
ogive – which is critical to accuracy.
Our Bullet Comparator easily attaches to the blade of your caliper with
a thumbscrew and uses interchangeable insert bushings to measure
from the bullet ogive. These bushings are available in fourteen (14)
sizes from .17 caliber to .45 caliber.
The Complete Set (B14) includes 14 inserts: .172, .204, .224
(5.56mm), .243 (6mm), .257, .264 (6.5mm), .277, .284 (7mm), .308
(7.62mm/8mm), .338, .358, .375, .416, .458.
When used in conjunction with the OAL Gauge, the Bullet Comparator
provides the ultimate in precision measurement. The Bullet
Comparator will properly align the OAL Gauge for proper, precise
measurement using your caliper. This method allows direct
comparison of your loads as you set up your bullet seating die for the
correct bullet free-travel (jump). Complete instructions included.
WARNING: This product contains lead, a chemical known to cause
cancer, birth defects and other reproductive harm.
Hornady Manufacturing Company
Box 1848, Grand Island, NE 68802-1848
www.hornady.com
69012
Item No. B14
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How to use: Attach Body to caliper blade with provided
Thumb Screw. The slot in the Comparator Body is
machined to allow either "off-center" or "on-center"
alignment with your caliper blade, depending on which of
the two threaded holes are employed.
Set
Screw
Thumb
Screw
Body
Bushing
OAL Gauge
(partially shown)
When using the OAL (Over-All Length) Gauge and Bullet
Comparator in combination, always attach the Comparator
Body to the "traveling" blade - in the off-center position then measure using the configuration shown in the
illustration. This method will align the OAL Gauge parallel to
your caliper. For all other uses, the Comparator Body may
be attached to either blade in the "on-center" position.
Place Bushing Insert (corresponding to bullet diameter) into
Comparator Body. Prior to measuring, close the caliper
blades snugly on the Bushing Insert and Comparator Body,
and tighten the Thumb Screw and Set Screw. Then, "zero"
your caliper (to 1.000") by setting the dial to “0” to achieve
the same starting point in future measurements. To take a
reading, open the caliper blades, center the case-head (or
bullet base) on the caliper's fixed blade and slowly close the
caliper so that the bullet nose feeds into the Comparator
until contact is made. Be certain all surfaces are aligned
and all slack is removed as light pressure is applied to
caliper blades (be consistent).
Insert
Traveling
Blade
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When setting up your seating die, compare your results
(using measurements taken with the Bullet Comparator)
with those from the OAL Gauge or a "dummy round."
Remember that as you reduce the cartridge OAL from
maximum, the difference will be "free-travel" (jump) to the
rifling.
Reducing bullet free-travel to closely match the chamber
dimensions can provide significant improvements in
accuracy. However, for hunting rounds we recommend that
bullets are seated at least .020" off the rifling to ensure
reliability in the field.
Remember: different bullets have different ogive curvature
(i.e. #6 vs. #10 ogive, and secant vs. tangent ogive). As a
result, the bullet free-travel (jump) may change as much as
1/16" or more when one bullet model is substituted for
another. Therefore a comparator cannot be used to transfer
dimensions from bullet style "A" to bullet style "B", as this
would be an "apples and oranges" comparison (the same
reason the mic's - which employ an imitation bullet produce errant results). When changing bullet models, it is
imperative to get new cartridge OAL dimensions from
reloading reference material, or from the firearm itself using
a bullet seating depth gauge. The best gauge for this
purpose is Hornady's OAL Gauge.
Hornady is proud to contribute a percentage of our
sales to the National Shooting Sports Heritage Fund
to foster a better understanding of and greater
participation in the shooting sports.
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