| Calculating additional
Powder and Shot settings
Note:
The supplied powder charts are given mainly in even grains.
Likewise, the supplied shot charts are given in eigth of an
ounze increments.
A simple fact, based on the design of the
scales on the bar and the scales on the adjusting knobs, makes
it possible to calculate quantities that lie in between two
quantities shown of the charts. Successful calculation requires
only elementary arithmetic.
This method, given below, applies to the
computation of settings
for BOTH powder and shot.
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FACT: Both the powder valve and the shot valve
are controlled by two scales each, one on the front edge of
the bar, the other on the adjustable knob at the end of the
bar. Just like feet and inches can be converted to inches, the
bar and knob scales can be easily converted to knob units. Remember,
one unit of the bar scale is equivalent to 40 units on the knob
scale.
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!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ALWAYS use common sense
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Regardless whether you are using charts,
your own calculations,
or those of someone else,
review ALL settings for logical consistency
B E F O R E loading and firing
a charge based on a given setting.
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How to make settings which are not shown
on the chart
The powder chart shows values in full grain-increments only.
Example:
SR 7625
{43 grs.} 14 + 13
{44 grs.} 14 + 30
SR 7625
Suppose one needs a charge of 43.5 grs. instead of 43 grs. or
44 grs. of SR7625 powder. The setting for 44 grs. of SR7625
is 14 + 30. The setting for 43 grs of SR7625
is 14 + 13. Subtract 13 from 30 = 17 increments.
Then divide 17 by 2, which is 8.5, and add the 8.5 to 14
+ 13 which then becomes 14 + 21.5. This setting
will give you a charge of 43.5 grs. of SR7625.
The same method can be applied to all other
charges and settings.
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How to get a 1/2 grain setting between two full
grain settings where one bar setting is, let's
say, 9 + 36
and the next higher setting is 10 + 12:
Example:
Blue Dot
{40 grs.} 9 + 36
{41 grs.} 10 + 12
Blue Dot
Explanation: How many increments
are there or, how many increments (or stitches on the knurled
knob) must the knurled knob be moved in order to get from 9
+ 36 to 10 + 12? To start, let's count: 1,
2, 3 to 0 for four increments.
Now let's look at the scale on the Bar-body:
the reference line on the valve is now aligned with line 10
and the line on the knob is at 0.
Therefore, this setting is 10
+ 0. To go from 10 + 0 to 10
+ 12, we have to move the knob another 12 increments (or lines,
or stitches).
Now, how many lines did we move on the knob
altogether? From 9 + 36 to 10 + 0 it is four lines plus another
12 lines to 10 + 12, makes it 16 lines.
If it takes 16 lines to go from 40 grs. of Blue
Dot powder to 41 grains of Blue Dot powder, how many lines do
you have to move the knob to throw 1/2 of a grain? Divide 16
by two and the answer is 8 lines.
Add 8 to 9 + 36, and one could
say, that one has a setting of 9 + 44.
But, since there is no such setting (or reading),
since there are only 40 lines on the knurled knob, we have to
move the knob four lines past the 0.
This reading then becomes 10
+ 4.
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We expect that the above examples will work
for everyone. A more general method is given below. You should
always get the same results with either method.
continues at G E N E R A L M E T H O D _____________________________________________________________________________ |
