Manual

and spaced .860" on center. Scopes should be mounted according to manufacturer’s in-
structions.
R. INTRODUCTION TO THE BALLISTICS TABLES
HOW VELOCITY WAS MEASURED
Two Oehler 35P Proof chronographs were employed to gather velocity data. One shot
was fired to “dress the bore” before testing for bullet velocity. The bore was swabbed between
test shots when blackpowder was used but not when Pyrodex was used.
WHY DATA VARIES
Two identical firearms will not produce identical velocities in spite of using exactly the
same load in each one. This is due to variables. Here are two:
1. No two bores are absolutely identical in diameter. The differences may be in minute
degrees, but bore diameters differ, thereby altering bullet drag (bore friction) ever so
slightly.
2. Rifling varies. Rate of twist, depth of groove, smoothness or roughness of lands, and
other incidentals all affect velocity.
POWDERS DIFFER
Blackpowder of today is not the same as blackpowder of yesterday. There are even small
differences in burning characteristics from lot to lot.
POWDERS MAY CHANGE IN COMPOSITION
Today’s Pyrodex, for example, is the best ever. It is “powerful.” That is, it yields good
energy per mass. And it is dense. In the past, there was approximately a 20% weight-per-
volume difference between Pyrodex and blackpowder. One hundred grains VOLUME of FFg
yielded very close to 100 grains WEIGHT, while 100 grains VOLUME of Pyrodex RS yielded
about 80 grains WEIGHT. Current Pyrodex is more dense. A 100 grain VOLUMETRIC setting
yielded, in tests, a mode (most repeated number) of 71.5 grains RS by WEIGHT, with a slightly
higher velocity potential per charge than older Pyrodex.
ELEVATION AND TEMPERATURE
Both elevation and temperature may alter velocity. A very hot day may bring slightly
higher velocities, as will high altitudes. These differences are of no practical concern, but they
exist.
ROUND BALLS MAY VARY
A test rifle may show different velocities when different round balls are used, in spite of
the different round balls being almost identical in caliber. A micrometer measurement may
prove that the two different round balls are not identical. Also, cast round balls may vary in
diameter and even weight compared with swaged round balls.
CONICALS MAY VARY
Different conical designs, in spite of being the same weight and caliber, may show slightly
different velocities due to varying bore friction. A bullet with a lot of shank (more drag), for
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