| Frequently Asked
Questions:
If you have read our introduction,
you have learned that our standard systems come in sets of three
cards, one for cold, one for moderate,
and one for hot seasonal
conditions. They are color-coded for quick and easy identification
and also have the temperature range listed on each card. This makes
the system more accurate than standard ballistics data which are
normally calculated at only 59o F. Very informative instructions and
tips are included with each set of Ballisticards.
Q: What brands of ammunition are
Ballisticards available for?
A: Most Ballisticards are specially
calculated for use with FEDERAL ammunition and matching handloads.
However, most of our systems are cross-referenced
for use with other brands of ammunition, so you are not limited to
only one load.
Q: What barrel lengths are
Ballisticards calculated for?
A: Most Ballisticards are calculated
for 24 inch barrels (custom
calculations are available) because it is a common length and
falls between 22 and 26 inches. A difference in barrel length of 2
inches, up or down, will not affect velocities as much as you might
think. Published SAAMI guidelines are as follows:
| Centerfire
Rifle Velocity vs. Barrel Length |
Muzzle
Velocity
Range (feet per second) |
Approximate
Change in Muzzle Velocity
Per One Inch Change in Barrel Length |
| 2000-2500
fps |
10
fps |
| 2500-3000
fps |
20
fps |
| 3000-3500
fps |
30
fps |
| 3500-4000
fps |
40
fps |
If we use these criteria as
guidelines, we see points of impact changing as follows, when going
from a 24 inch barrel to a 26 inch barrel (calculations based on a
200 yard zero):
| Cartridge |
Bullet |
Point
of Impact Change |
| .223 |
55gr.
SBT |
0.3"
@ 300 yds / 2.1" @ 500 yds |
| .308 |
168gr.
HPBT |
0.3"
@ 300 yds / 1.9" @ 500 yds |
| .300
Win. Mag. |
200
gr. SBT |
0.2"
@ 300 yds / 1.2" @ 500 yds |
As you can see, even at 500 yards the
difference is relatively insignificant. Allowing that most hunting
shots are well under 400 yards, the 24 inch barrel calculations we
normally provide will work well for most situations. For a worst
case scenario, if you were to chronograph your ammunition, in your
rifle, under your hunting conditions, and found that instead of a 30
to 40 fps per inch change in average velocity (10 shot minimum -
please), that there was a 50 fps per inch change (100 fps total),
you could simply move up or down to a "hotter" or
"colder" card - Note: velocities are listed at the top of
each card.
Q: What about altitude? Standard
Ballisticards are calculated for sea level and I hunt at 5,000 ft?
A: Ballisticards are very versatile!
A recent question came from a hunter in Canada. He was going on an
Ibex hunt in Siberia. The weather was to be well below freezing and
the altitude between 7,000 and 8,000 ft. When we ran his 30-06 load
through the computer, with that criteria, we found that by shifting
up, from the blue card to the green card for reference, that his
actual theoretical point of impact would be within 2 inches of the
point of impact indicated on the green card, at 500 yards! At 5,000
feet above sea level, the numbers were within a fraction of an inch!
One magnum load we checked came within 0.1" @ 5000 ft. by using
this method. When hunting at higher altitudes the air is less dense,
providing for flatter trajectories. Above 5,000 feet, you may do
well to simply move up to the next hotter card. If you want to get
fanatical about it, at around 2,500 feet, you could split the
difference between two cards, etc. For long-range tactical shooters
this could be valuable information! Note: Your actual
point of impact at different altitudes should always be tested and
verified, in your actual shooting conditions, prior to
relying on this method of compensation.
Q: What about humidity and barometric
pressure?
A: These variables have minimal
effect out to 500 yards. A good solid shooting position is far more
important!
Q: Do I have to change my sights
seasonally?
A: You should always re-zero in the
conditions that you anticipate hunting in. You may not notice much
difference at 100 yards, but at longer ranges you will. Keep all
ammo out of direct sunlight and allow it's temperature to stabilize
to ambient conditions. Let your barrel cool between shots and don't
leave a round sitting in a hot chamber any longer than necessary.
Otherwise, it will raise the cartridge temperature, and can change
the velocity and subsequent point of impact. A "cold barrel
zero" (at least five minutes between shots - or cool to the
touch) is advisable.
Q: What if I'm not into it that much
and really want to keep things as simple as possible?
A: Get a good solid zero, limit your
shots to within 400 yards, and use the green card year round.
Q: So what's the bottom line?
A: Nothing is perfect! But we're
getting closer. We can't control nature, but we can adapt in a way
never available before, by using this three-card system. Remember
the days when we felt confident with a small scrap of paper taped to
our stock? Look at what is available now! When you see all the
information on these three little cards and learn how truly
versatile they are, you'll never want to go back to guessing or
trusting to luck!

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