September 28th 2023The new ZEISS LRP 318-50 FFP scope is shown in the photo. “A bullet launched from a higher elevation is able fly slightly further (in the thinner atmosphere) for each increment of downward movement. The bullet behaves as though it had a higher ballistic index. “It is hunting season and we have a good friend who wants us to go to the high country in Colorado to hunt elk. He zeroed his gun in California at a distance of just a few hundred foot Above Mean Sea Level. He wondered if Colorado’s higher altitude would affect his ballistics. The answer is yes. The answer is a resounding yes. The simple answer is that at higher altitudes the air is thinner and denser, so the bullet is less dragged. This means that there is less bullet drop at any given distance from the muzzle. The bullet’s downward speed doesn’t change because the force of gravity on earth’s surface is constant. However, a bullet that is launched from a higher elevation can fly farther (in thinner air) with every inch of downward movement. Forum member Milanuk explains the key factor to consider is air pressure, not altitude. Milanuk writes that as altitude increases, air density decreases. This reduces the drag of the bullet. The higher the altitude the less the bullet drops. I shoot at two ranges in the Pacific Northwest. Both are at 1,000? AMSL (Above Mean Sea Level) or less. I’ll require about 29-30 MOA for a Berger VLD 155gr at 2960 fps to get from 100 to 1000 yards. In Raton, NM located at 6600 feet? AMSL, it will only take me about 24-25 MOA. This is a big difference. It is not the nominal altitude that matters, but the barometric (or atmospheric) pressure. The barometric will show you the reduced pressure at a higher altitude but also the pressure changes when a front moves into the area. This can mess up your calculated come-ups. Most altimeters simply read barometers in feet rather than inches of mercury. As Milanuk says, it’s not the altitude itself, but the local barometric pressure, also called “station pressure”, that is important. The barometric pressure and air temperature are the two atmospheric conditions most important to bullet flight. Humidity has a negligible impact. Remember that the barometric readings on the radio or internet may be expressed as an equivalent sea level. If the local pressure in Denver (at 6,00 feet AMSL) is 24? then the radio will report a barometric pressure of 30?. Bring a Kestrel or mentally correct the pressure of the radio station by 1? when you are shooting at high altitudes. The bullet trajectory at sea level.
Trajectory shot at 20,000 feet
JBM Online Ballistics is a free tool that you can use to perform your own calculations. Here is a very extreme example. Two printouts were generated with Point Blank software, one showing bullet trajectory in the sea level (0? For demonstration purposes, we assigned a low 0.2 BC to the bullet with a velocity of 3000 fps. To demonstrate, we used a bullet with a low BC of 0.2 and a velocity of 3000fps. Hornady’s discussion of External Ballistics includes the effects of temperature and altitude. Sierra Bullets offers a comprehensive Exterior Ballistics Resources Page that includes multiple sections from the Sierra Manual (4th & 5th Editions).
Section 3.1: Altitude and Atmospheric Conditions
Section 3.2: Wind Effects
Section 3.3: Effects on Shooting Uphill and DownhillExample taken from Section 3.0: When a bullet flies in the air, it is affected by two different types of forces. The first force is gravitational; the second is aerodynamics. There are several types of aerodynamic forces that act on a bullet. These include drag, lift forces, side forces and Magnus forces. Drag is the most important aerodynamic force. “All the other forces are small in comparison to spin stabilization.”
Similar Posts Tags: Altitude, BC, Ballistics, Kestrel Trajectory, Kestrel Density Altitude
