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July 18th, 2015
The Swarovski Optik website features a blog with interesting technical articles. In the “On Target” series of blog stories, Swarovski has provided a handy explanation of how optics systems work, with exploded diagrams of rifle scopes, spotting scopes, and binoculars. CLICK HERE for Swarovski Optics Blog.
Scope Terminology
Focusing Lens
The focusing lens is an adjustable lens inside the optical system for focusing the image at different distances…. In the case of rifle scopes, apart from focusing, the focusing lens also facilitates parallax compensation.
Diopter Adjustment
For rifle scopes, the reticle can be focused using the diopter adjustment on the eyepiece, thereby correcting any visual impairment. [Editor’s Note: Movable eyepiece diopter adjustment is not offered on all rifle scopes. It is a useful feature on Swarovski and other premium scopes. This allows shooters who need eyeglasses to get a sharply focus image even without wearing corrective lenses. Of course shooters should always wear ANSI-certified eye protection. With the diopter, folks who need correction can use inexpensive, non-Rx safety eyewear instead of expensive prescription safety glasses.]
Reversal System
The purpose of the reversal system is to reverse the image by means of prisms in binoculars and telescopes, and lenses in rifle scopes….The lens reversal system is needed in rifle scopes to control the variable magnification and move the exit pupil[.]
Resource tip by EdLongRange. We welcome reader submissions.
July 16th, 2015
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.
 This 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:
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.
July 12th, 2015
Here’s a smart new product that could save your life (or the life of a loved one). The EPIC-id bracelet stores your vital information on a shockproof, weatherproof USB flash drive that can be instantly accessed by an EMT or doctor. Your Editor just bought two of these med-info bracelets — one for himself and another for a diabetic family member. If you’re a shooter, or spend much time outdoors, you should have this device or some other kind of tag that provides your vital info (such as blood type and drug allergies) to first responders.
If you’re injured, first responders need to know if you have a medical condition, have drug allergies, or take any medications. With this bracelet, that vital info is available even if you can’t communicate. The EPIC-id Emergency Band stores medical data on a USB flash drive that can be “read” by any computer or mobile device with a USB port. Firefighters, EMTs, and medical professionals can instantly determine your name, emergency contacts, insurance, and medical information. (Read my experience below).
It’s easy to load your medical data on to the device. Standardized emergency info forms come pre-loaded — just insert the Epic-ID into any computer to fill out the forms. PC and Mac™ compatible, the waterproof EPIC-id features a durable stainless steel clasp and trim-to-fit silicone band.
Editor’s Story — Why This Is Important
Just this past Wednesday July 8th, at 2:00 am, a family member was rushed to the hospital after suffering a stroke. She was non-responsive and unable to communicate at all. This created problems for EMTs because they were unaware of her current medications, insulin needs, resusitation preferences, and some relevant past medical history. After that experience I decided to buy these bracelets for her and myself. The good new is that she survived… but it was close.
July 8th, 2015
While many of us now favor digital photography over “old-fashioned” 35mm film, don’t toss those old 35mm film canisters, especially the clear Fuji-type with secure snap-in lids. Small plastic film canisters have a multitude of uses for the shooter and reloader.
Here Are Things You Can Do with Plastic Film Canisters:
1. If you weigh powder charges after throwing them with a manual powder dispenser, throw the charges first into a film canister and then use that to drop the powder into the measuring pan on your scale. The canister will catch every kernel of powder. If you throw charges directly into a weighing pan, powder can sometimes bounce out. Using the film canister will help keep spilled powder off your loading bench and floor.
2. Store extra sets of foam ear-plugs in the canister. You never want to be without ear protection. This editor has four film canisters filled with plugs. Two go in the range kit, one goes in the car’s glove compartment, and a second stays in a lock box I use to transport pistols. This way I never find myself at the range without ear protection.
July 2nd, 2015
 Forum member Rich DeSimone uses a handy “Stub Gauge” for setting shoulder “bump” and seating depth. The gauge is made from a section of barrel lopped off when the muzzle is crowned. The chambering reamer is run in about 1/4 of the way, enough to capture the neck and shoulder area of the case. Rich then uses his full-length die to “bump” a master case with the ideal amount of headspace for easy feeding and extraction. He takes that case and sets it in this Stub Gauge, and measures from the front of the gauge to the rim. He can then quickly compare any fired case to a his “master” case with optimal headspace. Since the gauge measures off the shoulder datum, this tells him how much to bump his fired brass.
In addition, the Stub Gauge can be used to set bullet seating-depth. Rich has a channel cut transversely on one side of the gauge, exposing the throat area. Since the interior of the gauge is identical to the chamber in his gun, this lets him see where a seated bullet engages the rifling. He can tinker with bullet seating length until he gets just the right amount of land contact on the bullet, confirmed visually. Then he measures the case OAL and sets his seating dies accordingly. This is much handier than using a Stoney Point Tool to measure distance to the lands. As your barrel’s throat wears, you may seat your bullets out further to “chase the lands”, but the gauge provides a constant land engagement point, in the barrel’s “as new” condition. By measuring the difference between the land contact point on the gauge and the actual contact point on your barrel, you can determine throat “migration”.
June 14th, 2015
The .260 Remington and the 6.5×55 Swedish (aka 6,5x55mm SE) are both very popular cartridges with hunters and target shooters. The 6.5×55 has a long military heritage and a great record as a hunting round. The .260 Rem, essentially a .308 Win necked down to .264 caliber, is a more recent cartridge, but it grows in popularity every year, being one of the top cartridges for tactical/practical competitions. It offers better ballistics and less recoil than the parent .308 Win cartridge. In our Shooter’s Forum, respected UK gun writer Laurie Holland provided a good summary of the differences between the two chamberings. Laurie writes:
 The 6.5×55 case has 6 or 7% more capacity than the .260s, even more in practice when both are loaded to standard COALs with heavy bullets, which sees them having to seated very deep in the .260 Rem using up quite a lot of powder capacity. So loaded up for reasonable pressures in modern actions, the 6.5×55 will give a bit more performance.
The issue for many is what action length is available or wanted, the 6.5×55 requiring a long action. So sniper rifle / tactical rifle competitors will go for the .260 Rem with the option of the many good short-bolt-throw designs around with detachable box magazines (DBMs). If a bit more performance is needed, the .260 AI (photo right) can yield another 100-150 fps velocity, depending on bullet weight.
June 14th, 2015
 Berger Twist-Rate Stability Calculator
On the updated Berger Bullets website you’ll find a handy Twist-Rate Stability Calculator that predicts your gyroscopic stability factor (SG) based on mulitiple variables: velocity, bullet length, bullet weight, barrel twist rate, ambient temperature, and altitude. This very cool tool tells you if your chosen bullet will really stabilize in your barrel.
LIVE DEMO BELOW — Just enter values in the data boxes and click “Calculate SG”.
June 7th, 2015
You never want your barrel to get too hot. Accuracy suffers when barrels over-heat, and excessive heat is not good for barrel life. So how do you monitor your barrel’s temperature? You can check if the barrel is “warm to the touch” — but that method is not particularly precise. There is a better way — using temperature-sensitive strips. McMaster.com (a large industrial supply house) offers stick-on temp strips with values from 86° F to 140° F. A pack of ten (10) of these strips (item 59535K13) costs $10.71. So figure it’ll cost you about a buck per barrel for strips. That’s cheap insurance for your precious barrels.
June 6th, 2015
Western Powders (vendors of Accurate, Norma, and Ramshot powders), publishes a Blog that covers all aspects of hand-loading and rifle maintenance. Recently the Western Powders Blog published a Q & A series entitled Dear Labby: Questions for our Ballistics Lab. Here are some excerpts that pertain to powder storage and shelf life. Worried that your powder may be too old? Western’s experts explain how to check your propellants for warning signs.
Proper Powder Storage
Q: I live in southern Arizona where it is very hot. I am told powders will become unstable if stored in an area not air-conditioned. My wife says no powder or primers in the house. Can powder be stored in a refrigerator? What about using a fireproof safe? I would appreciate your ideas. — M.C.
Lab Answer: SAAMI guidelines are pretty clear on issues of storage. They recommend storing smokeless powder in containers that will not allow pressure to build if the powder is ignited — ruling out gun safes and refrigerators.
CLICK HERE to Read SAAMI Guidelines for Powder Storage (PDF)
June 1st, 2015
On some internet shooting forums, self-declared “experts” advise new rifle shooters to stick to low-end factory rifles. These “experts” (many of whom don’t own a single really accurate rifle), claim that it will take years for a new shooter to learn how to shoot a rifle accurately. So, the argument goes, the accuracy offered by a precision-chambered rifle, with a custom barrel, is “wasted” on a new shooter.
We disagree with that viewpoint, at least when it comes to rifles shot from a rest. Certainly it takes time for a complete novice to learn how to handle the gun and to work the trigger smoothly. However, we’ve seen relatively new shooters, with help from a skilled mentor, do remarkably well with precision rifles right from the start. With a good bench gun, many new shooters can shoot well under 1 MOA on the first day. This editor has personally seen some inexperienced ladies try their hand at benchrest shooting, and within a month or two they are shooting on a par with the “good old boys” in serious competition.
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