The Pressure is On: Barometric Pressure and Precision Shooting
July 10th, 2020 by BALLISTIC
For most people, “Barometric Pressure” is just a number on the weather app, and often ignored because we want the crucial info: Is there rain on the way? Warm today, or cold?
For the long-range shooter, though, barometric pressure is a significant factor in making solid hits. There’s no better way to factor in the barometric pressure than by using Ballistic, the #1 long-range shooting app.
Barometric Pressure, also called Atmospheric Pressure, is the amount of pressure present in the air at any given place at any given time. Think of it this way: the Earth is surrounded by a layer of gasses, the “atmosphere.” At sea level, this layer is at its thickest (from the ground to atmosphere’s end), and this equates to lower barometric pressure, compared to the top of a mountain where the pressure is less (less air mass above the top of the mountain) and therefore creates higher barometric pressure.
Weather fronts moving in or out can also greatly affect barometric pressure.
Barometric pressure is often measured in inches. The higher the number, the higher the barometric pressure, and vice-versa.
What does all this mean for the long-distance shooter? Well, at a higher barometric pressure, a bullet experiences less resistance. Therefore, it will drop less than the same bullet moving at the same speed through air with a lower barometric pressure.
For example, consider a rifle chambered in 6.5 Creedmoor, the ammunition loaded with a 140-grain Hornady ELD Match bullet. Muzzle velocity is 2,710 feet per second, and the rifle is set with a 100-yard zero.
At the same altitudes, but at very different barometric pressures, the bullet drop between these two scenarios is significantly different. For an extreme example, Ballistic Pro Shooter Logan Brown notes that at a high barometric pressure of 30.00 versus an extremely low pressure of 25.00, the difference in the above bullet’s trajectory at 1,000 yards can be nearly 30-inches.
Best advice: Logan says to update your Atmospheric Conditions on Ballistic as you move from place to place, and as weather fronts move in and out. Ballistic will automatically recalibrate your projectile’s trajectory based on the atmospheric inputs and changes to those inputs, placing you on target no matter the conditions.
On target, whatever the conditions: that’s the Ballistic promise!
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