July 16th, 2015

Barnes Calculates Ballistics Using Doppler Radar Speed Data

Ballistics Barnes Bullets Doppler Radar G1 G7 curve model drop chart DOF 6 degree of freedom

How do you build better (more precise) ammo drop tables? With radar, that’s how. Barnes Bullets is using Doppler Radar to develop the drop tables for its new Precision Match line of factory ammunition. The Doppler radar allows Barnes to determine actual velocities at hundreds of points along a bullet’s flight path. This provides a more complete view of the ballistics “behavior” of the bullet, particularly at long range. Using Doppler radar, Barnes has learned that neither the G1 nor G7 BC models are perfect. Barnes essentially builds a custom drag curve for each bullet using Doppler radar findings.

Use of Doppler Radar to Generate Trajectory Solutions

by Barnes Bullets, LLC
Typical trajectory tables are generated by measuring only two values: muzzle velocity, and either time-of-flight to a downrange target, or a second downrange velocity. Depending on the test facility where this data is gathered, that downrange target or chronograph may only be 100 to 300 yards from the muzzle. These values are used to calculate the Ballistic Coefficient (BC value) of the bullet, and the BC value is then referenced to a standardized drag curve such as G1 or G7 to generate the trajectory table.

Ballistics Barnes Bullets Doppler Radar G1 G7 curve model drop chart DOF 6 degree of freedomThis approach works reasonably well for the distances encountered in most hunting and target shooting conditions, but breaks down rapidly for long range work. It’s really an archaic approach based on artillery firings conducted in the late 1800s and computational techniques developed before the advent of modern computers.

There is a better approach which has been utilized by modern militaries around the world for many years to generate very precise firing solutions. Due to the sizeable investment required, it has been slow to make its way into the commercial market. This modern approach is to use a Doppler radar system to gather thousands of data points as a bullet flies downrange. This radar data is used to generate a bullet specific drag curve, and then fed into a modern 6 Degree of Freedom (DOF) [ballistics software program] to generate precise firing solutions and greatly increase first-round hit probability. (The 6 DOF software accounts for x, y, and z position along with the bullet’s pitch, yaw, and roll rates.)

Barnes has invested heavily in this modern approach. Our Doppler radar system can track bullets out to 1500 meters, recording the velocity and time of flight of that bullet every few feet along the flight path. Consider the graph below showing a bullet specific drag curve referenced to the more common G1 and G7 curves:

Ballistics Barnes Bullets Doppler Radar G1 G7 curve model drop chart DOF 6 degree of freedom

Neither of the standard curves is a particularly good match to our test bullet. In the legacy approach to generating a downrange trajectory table, the BC value is in effect a multiplier or a fudge factor that’s used to shift the drag curve of the test bullet to try and approximate one of the standard curves. This leads to heated arguments as to which of the standardized drag curves is a better fit, or if multiple BC values should be used to better approximate the standard curve (e.g., use one BC value when the velocity is between Mach 1 and Mach 2, and a different BC value when the velocity is between Mach 2 and Mach 3.) Barnes’ approach to creating trajectory tables is to generate bullet-specific drag curves, and use that data directly in a modern, state-of-the-art, 6 DOF ballistics program called Prodas to generate the firing solution.

Story tip from EdLongrange. We welcome reader submissions.
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July 16th, 2015

Eye Protection — What You Need to Know

Eyewear Safety Eye Protection Glasses Guide

There is one subject as to which we should all be in agreement — the need to wear quality, protective eyewear whenever one uses a firearm. Sadly, it’s not uncommon, at the range, to see shooters wearing no eye protection, or wearing cheap, “dime-store” glasses that can shatter on impact.

This video from Luckygunner Labs shows what can happen with low-quality eyewear. When hit with pellets, the left lens came out and the right lens entered the eye socket!

Read Our Guide to Protective Eyewear

We’ve created a comprehensive Guide to Protective Eyewear. Forum member ChuckW2 told us: “That was the most important article that has ever been posted on this site. I am amazed how many people do not wear glasses while shooting or hunting. Great read….” If you haven’t done so already, read the story. We guarantee you’ll learn something new.

CLICK HERE to READ Comprehensive Eyewear Guide

The Eyewear Guide explains the safety standards that apply to protective eyewear and reviews the best lens materials currently available including Polycarbonate, Trivex™, and SR-91. You may not have heard of Trivex, but it is probably the best material out there right now — it’s tough, lightweight, and has better optical properties than Polycarbonate. SR-91 is a good choice for those who need a polarized lens. Our Eyewear Guide also includes a section by Danny Reever on Prescription Shooting Glasses. Danny discusses the available options in lens materials and has many helpful recommendations.

Along with our reviews of lens materials, tint properties, and frame design, we highlight a study done by the NRA’s American Hunter magazine. 10 popular brands of eyewear were tested, with some very interesting results. The testers observed that price does not necessarily assure quality. Relatively inexpensive Bollé VX and Pyramex eyewear both worked better than some expensive brands.

On the other hand, don’t select eyewear simply because it’s cheap or easy to find. American Hunter editor Jeff Johnston observed: “It’s a mistake to assume that any plastic-lens sunglasses off the rack at the local 7-11 are made of polycarbonate and therefore are effective as shooting glasses—cheap plastics are not polycarbonates; in fact, wearing them could be worse than wearing nothing, as they can introduce sharp shards of plastic to your eyes in addition to the projectile(s) that caused them to break.”

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July 16th, 2015

Zeiss Summer Field Days Optics Rebates

Zeiss Rebate Summer binoculars Ballistics Reticle

We all know Zeiss makes good optics, and now you can save $50-$150 on Zeiss binoculars or Zeiss riflescopes. As part of the Zeiss Summer Field Days promotion, Zeiss is offering $50.00 cash back on select scopes and binoculars (and $150.00 on the Victory HD binos). Hunters may want to take advantage of this offer for the CONQUEST HD5, and Victory HT Scopes with RAPID-Z ballistic reticles. Those are nice optics. To claim the rebate, purchase eligible products between 7/1 and 8/31/2015 at any participating ZEISS Authorized Dealer, then visit the Zeiss Online Rebate Center to register your rebate. Be sure to save your product receipts.

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