Re: Do weather meters = better LR consistency?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ToKeepAndBear</div><div class="ubbcode-body">Just wondering if the portable weather meters (Kestrel, etc.) do improve LR consistency (especially first round hits)? I would think so, but want to get some real world feedback. </div></div>
I use a Kestrel 4500NV with built-in atrag software. It is useful but it's not complete.
The Kestrel meter has these sensors:
Wind velocity - impeller which must be pointed into the wind
temperature sensor - air temperature at the kestrel instrument
air pressure sensor- absolute pressure sensor
humidity sensor - relative humidity not waterproof
2D flux gate compass - measures magnetic azimuth with meter held vertical.
time interval clock - measure time between key presses for moving target calculation.
To use the atrag calculator additional information is needed.
Before going shooting:
rifle/cartridge/bullet ballistics data (stores 50 combinations)
Latitude - used only for coriolis calculation
magnetic declination - to calculate true north azimuth from magnetic azimuth.
When target is identified:
range to target - manually entered either from a rangefinder or it can do the calculations with input from a stadia range finder (mil-dot or Horus).
inclination to target- manually entered - guess or measure it with an inclinometer. My rangefinder measures inclination.
Measure target angular velocity - for moving target
When ready to shoot:
Update wind reading - ballistic calculation completed. elevation and windage are displayed in mils (or other) to count scope clicks or put target in place on a Horus mil grid.
Take the shot.
When a wind reading is taken the meter must be pointed into the wind. It stores the velocity and the magnetic azimuth. You also need to enter the target azimuth. You can use the meter to measure that by pointing the meter towards the target instead of into the wind. The computer converts the magnetic azimuths to true azimuths and calculates fore, aft, and crosswind components of the local wind.
There is a feature to calculate the temperature effect on muzzle velocity as a function of powder temperature, but it assumes the powder temperature is the same as ambient, which may or may not be the case. (black rifle in sunlight for example).
The only important thing which the system (kestrel+rangefinder+inclinometer) does not account for is downrange wind, which the Kestrel or the atrag software knows nothing about. It's up to the shooter to "dope" the downrange wind deflection difference from the local calculated wind deflection and and add or subtract it. In some terrain that may be close to zero correction, or it can be way off particularly in mountainous terrain. The Kestrel/atrag does handle drop calculations very well unless there are vertical downrange wind components, which the Kestrel knows nothing about.
The Kestrel has a moving target calculation feature which uses the meter's timer in conjunction with a stadia reticle (in the rifle scope) to measure and account for target angular velocity. The software doesn't account for cant. Use a level on the rifle to eliminate that error source.
Does it guarantee first shot accuracy? Only if you have the skill to dope downrange wind deflection. I don't know of any commercial instrument which does that. First shot accuracy is the holy grail, but it's no always possible do dope downrange wind well enough. There may not be enough visible clues. The use of a Horus mil grid reticle makes second shot corrections very fast and easy if you can see the first bullet's impact point. A spotting shot is by far the most accurate and most affordable wind meter avaialble to shooters. When it's usable it eliminates the need for a wind meter or ballistic computer at all.
Before you rush out and buy a Kestrel with atrag software give considerable thought about what's limiting your present first shot accuracy. Test that with your rifle and targets set at various (long) ranges in the conditions where you want to shoot. If your accuracy (first shot or other) is limited by downrange wind then your money would be better spent on ammo and time for practicing doping wind. If variable drop from velocity or air density variations is limiting then the Kestrel/atraj should be worthwhile.
I've become a believer in Horus reticles rather than knob twiddling and counting clicks. It's a much faster method with equal accuracy.
