Kestrel 4500 NV weather meter with Horus ballistics

Two years ago I spent four weeks putting the Kestrel 4500 NV with Horus ballistics through its paces, and although I liked the product and found it effective, I never learned to love it. When the similar 4500 NV with Applied Ballistics was launched, I decided to perform an extended test because the features offered by these units require serious study. It is impossible to cover all its abilities in two pages but this time I had a definite conclusion.

What is Different?

Visually identical to the Horus, the Applied Ballistics differs only by external labelling to the casual observer. The same five year warranted body, impeller, moisture and pressure sensors nestle in the compact handheld unit weighing only 102 grain and 130 x 45 x 25mm dimensionally. A lanyard and carry case is included and the unit runs on two supplied AAA Energiser batteries (more about which later). After installing the batteries and powering up there are certain calibration tasks to perform and others you are warned not to touch. Time, date etc. are entered along with a newly, more extensive setup configuration data log of up to eight guns with their calibres, projectile variables, B.C. and more to record. Bullet length is critical to spin drift and stability setting along with barrel twist rate and direction. Everything is done with eight rubberised buttons on the front using the LCD display window which can also be subtly NV illuminated a deep red colour (accompanied by a faint humming noise). Five languages are catered for and the unit is waterproof and buoyant. The impellor clips in and out for easy replacement if it is damaged as they are lightweight. With respect, the accuracy demands delicacy in this key component (the impeller can detect a human breathing at two feet)

The Air That I Breathe

All the same atmospheric parameters are monitored constantly to calculate a firing solution (the list is seemingly endless) alongside known input variables. The immediately obvious ones are range and wind speed/direction, but when you really start to test your long range shooting, certainly beyond 300 yards, wind is not the only critical factor. The further you shoot the more humidity, temperature, altitude/air pressure etc. factor in and, I must admit I don’t even get close to noticing the tiny variables attributable to some, like Coriolis acceleration for example, but for those who push the envelope, compensating all variables is imperative. For example, Spin Drift is actually more important in my shooting than altitude. Shooting mainly in the UK, topography and temperature are miniscule compared to the United States for example! Applied Ballistics refers to the involvement of data and software from Brian Litz, the ballistic guru from Berger Bullets whose modern take on G7 ballistic coefficients rather than G1 values, are all measured and recorded empirically rather than just mathematically. The inclusion of Drop Scale factors is also new and allows input of your own field data into the Kestrel to refine ballistics into the envelope of transonic (1.1-0.9x speed of sound) flight where unpredictable disruption is usually encountered and further subsonic progress, which is generally understood.

Instructions

A small instruction booklet is included inside the case, but I recommend going to the Kestrel website and downloading a set to print out on A4. Although it isn’t hard to get this unit up and running in 30 minutes, its talents run very deep requiring thorough understanding and it is an on-going task. The more you use it, the more you learn, and I will honestly admit to not fully appreciating the previously tested Horus model before. Of every item I have ever tested for this magazine, this is far and away the most complex but after six weeks of its use, with just one main rifle I am now utterly convinced.

So What Does It Do?

Imagine a 400 yard shot on a bearing of zero degrees north. Enter these into your current target solution and include an up/downhill angle for the terrain. Now press ‘Capture’ in the wind mode and watch the numbers dance! As you hold the unit facing into the wind, the Kestrel calculates all its measurable variables along with wind speed and relative direction to the line of flight of the bullet. You can twist and turn to get the wind equally on both your ears for an approximate directional bearing but the unit makes a close call on your behalf and it is uncanny how well it works. The solution updates every few seconds and it’s a great learning tool as you often start to see identifiable trends, windows in time to pull a trigger. Don’t get me wrong, it isn’t infallible and can’t compensate for downrange wind speed/direction variables but you are starting out with a fantastic ballpark solution. After four weeks and hundreds of rounds fired in variable conditions and locations, with many corrections and updates to variables and cross checks performed with real world results entered into the computational algorithms, the unit becomes increasingly refined and accurate.

Don’t Get Complacent

Before I became fully at ease with the reliability of the unit, I did discover one or two Achilles’ heels to be aware of. The first is that there are so many variables that can be altered, all equally accessible, and you have to be very careful making sure you alter what your intend to. The second is that the internal compass that sets both your firing direction and then relative wind direction was a little temperamental. The instructions warn you to calibrate the compass whenever you open the battery compartment and to be sure to use the battery separator (a thin plastic wedge) as the magnetic field developed by the two AAA cells can make things go wrong. I changed the batteries as the calibration mode itself worked intermittently with the supplied Energiser batteries but Duracell’s caused no problem. It isn’t a complaint, these devices are finely tuned whereas batteries are chemically churned out by the million, just be aware to look out for it as once detected and solved it has never happened again.

Conclusion

Like any complex machine, you still have to keep your brain in gear and I expect likely buyers of this kit to already have a fairly natural feel for its applications, functions and potential pitfalls. A few good solid hours will initiate all that is needed to further intuitively operate the unit and then, every time you shoot, record and re-evaluate the data (as you should always try to do) then perhaps input new info and allow your Kestrel to evolve into the tool it was born to be. It won’t be perfect first time but will be closer than any smartphone app with the ability to work forwards with data rather than backwards from results.

Is it a toy? Definitely not; it’s part of my armoury now. The Kestrel 4500 NV Applied Ballistics is priced at £552 (£654 with Bluetooth connectivity) and has a five year warranty. For more information visit the Richard Paul Russell Ltd website at www.r-p-r.co.uk.