Here's how you can tell if ballistics software
is technically correct.
Most software publishers allow you to download a demo of their
software so that you can try before you buy. Once a demo is
installed, it takes only a few minutes to test the technical
correctness of the software.
1. Check if the software calculates the effects of head
and tail winds on downrange velocity. This is easy to test,
just enter some convenient values for muzzle velocity, ballistic
coefficient, and bullet weight. Next enter a wind speed of around
20 MPH and set the direction to be a head wind (12 O'clock or
0 degrees), and record the calculated velocity for 500 yards.
Now change the wind direction to be a tail wind (6 O'clock or
90 degrees) and compare the head and tail wind velocities at
500 yards. The velocity of the bullet with the tail wind should
be higher than the velocity of the bullet with the head wind
by anywhere from 1 to 10 percent depending on the particular
values you entered. What you will find, however, is that most
software reports the same velocity regardless of the direction
of the wind and that's wrong.
2. Compare the program's calculated velocities to that
of a trusted source. Many of the reloading manuals include
ballistics tables, but some of them don't agree with each other
and are probably wrong. Without a doubt, the most scholarly
treatment of exterior ballistics is found in the Sierra Bullets
reloading manuals, but starting with edition 5, Sierra no longer
publishes ballistics tables. The tables in Nosler's fifth edition
and Hornady's sixth edition volume 2 agree with the tables published
in Sierra's edition 4, so they are the gold standard. If you
have either the Nosler or Hornady manuals you can check the
accuracy of a program's calculated downrange velocity values
with the tables in these manuals. The tables are for standard
sea level conditions, so be sure the program is using standard
conditions as well. Also, make sure you are comparing values
at the same range. Some of these manuals have tables with range
in meters rather than yards.
We have checked Ballistic Explorer extensively against the
Hornady tables and found nearly an exact match. With other software,
however, you will find that the calculated velocities are off
by 10 to 50 f/s second at 500 yards. The real advantage of software
is that it's not limited to standard conditions, but if it's
not correct a sea level conditions, it's not going to be correct
for other conditions.
Ballistic Explorer doesn't address internal ballistics and
here is why. Many factors that can be ignored in 20 mm and larger
calibers become highly significant in sporting calibers. It's
impossible to accurately predict pressures in sporting calibers
without considering these factors. The best that can be achieved
with current models is a usually safe (reasonable) powder charge.
Of course, the publishers of internal ballistics programs will
disagree, but you can check for yourself.
A number of newer reloading manuals were developed using modern
pressure measuring equipment. Examples include the current reloading
manuals by Hornady, Nosler, Sierra, and Swift. Run the internal
ballistics software on some convenient load and then compare
it to a load of the same caliber, bullet, and powder type in
a trusted reloading manual. What you will often find is that
the optimal load reported by the internal ballistics program
is below the starting load in the manuals. It's good these programs
error on the side of safety, but just imagine the anxiety you'll
go through working up to factory ammo velocities when the software
is predicting dangerously high pressures. Of course you can't
depend on the software always being wrong in the same direction,
so you'll still need your reloading manuals.