2013年8月6日星期二

Adjusting the balance of bullets - 02

By placing a plastic ball into the jacket, compressing it, and then placing a small quantity of
tungsten powder in the jacket followed by a final plastic ball, the weight can be increased and the
balance shifted, so that a combination of material quantities and positions can be developed that will
deliver good stability with any of the weights. Moving the weight toward the tip tends to make the
bullet more stable, but a point will be reached where the bullet does not turn to follow the trajectory
arc. At that point, the bullet is “over-stable” in the sense that rifling no long is required to keep it
pointed nose first, but instead the mass forward of the center of form will do this. If the trajectory is
very flat, or the range is quite short, the bullet will appear to be accurate.
But if the trajectory or range is normal for a rifle or long-range handgun, the bullet will be
pointed in the same direction as it was when it emerged from the barrel all the way to the target. That
is, it refuses to turn because it is so stable. In this case, the bullet presents an angle to the direction of
flight and thus offers a very low ballistic coefficient, compared to the same bullet with the center of
gravity shifted slightly further toward the rear. Extreme examples have resulted in the bullet dropping
sideways through the target (and the normal wind and air currents cause it to drift in an extreme
pattern from shot to shot, which appears to make the bullet seem inaccurate—and in practical terms,
it is).
You may visit our website www.tungsten-powder.com to get more details.

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