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March 21st, 2013

Mirage Shields — Not Just for Benchresters Anymore

AccurateShooter Mirage ShieldMirage shields really do help you hit your targets more reliably. Novice shooters may wonder “Why does that guy have a venetian blind attached to his barrel?” Here’s why. As the barrel gets hot, the heat from the barrel rises up, cooking and distorting the air directly in front of the scope’s front lens. In essense, the rifle creates its own nasty visual mirage, right in the worst possible place. You can have a $4000.00 custom rifle and a $2500.00 scope but if the air in front of your scope is distorted, it can literally move your apparent point of aim on the target relative to your cross-hairs, causing you to miss the shot.

As our friend Boyd Allen observed: “Varminters should use mirage shields. Think about it. You’ve invested thousands of dollars in a fancy varmint rifle and quality scope. You may have spent hundreds of dollars traveling to the varmint fields and spent dozens of hours loading up your ammo. Without a mirage shield on your barrel, once that barrel gets hot, you WILL get mirage effects that can make you miss a shot.”

So, we’ve established you need a mirage shield to shoot your best when the barrel gets hot. You can make your own shield from a scrap blind, or purchase a ready-made plastic or aluminum shield. Sinclair Int’l offers 2″-wide, white mirage shields in 18″ (#06-7200) or 24″ (#06-7300) lengths for $4.95. Shotmaster 10X offers a variety of Patterned Mirage Shields, starting at $6.00. These include a Patriotic theme and even Tiger Stripes:

ShotMaster 10X mirage shields

Camo Mirage Shields for Tactical Shooters and Hunters
Though tactical shooters should use mirage shields for long-distance, slow-fire stages, for the most part, tactical shooters don’t bother. One reason is that mirage shields CAN detach if you’re crawling around in the bush. However, for many tactical shooting situations, a mirage shield IS both practical and recommended. And now, for the first time, tactical shooters can get mirage shields in camo patterns to match their rifles. These camo shields should also be popular with varminters and long-range hunters.

ShotMaster 10X mirage shields

At the request of AccurateShooter.com, Shotmaster 10X created a line of camo-pattern mirage shields (see above). Made of 2″-wide aluminum strips, these are available in 18″, 20″, and 24″ lengths. The camo-pattern shields come complete with Velcro attachments, and start at $8.50 for the 18″ length. The 20″ models are $9.50, while 24″ shields are $11.00.

Permalink Hunting/Varminting, New Product 9 Comments »
December 8th, 2012

Wind Reading Tips for F-Class and Long Range Shooting

by Steven Blair, 2012 California State Long Range F-Open Champion

Assess the Terrain and How the Wind Will Interact with It
Before you begin a match, take a few minutes to look around the range at the terrain, any obstructions, range topography (berms and backstop), and trees, buildings or structures that could affect wind flow over the range. Imagine what might happen if the wind was from the left or right, headwind or tailwind. Depending upon the direction, significant effects may be seen on range. A head or tail wind may ripple across the berms, causing elevation changes, both high and low. A tall side berm, like the east side berm at Ben Avery, may cause turbulence when the wind comes from that direction. Blocking features might shield most of the wind but a break along the range can funnel strong gusts through the gap with no other indications. Take a few notes about the effects of different wind directions and refer to them if the prevailing direction changes. (Tip courtesy Tony Robertson.)

Steven Blair F-Class Wind Tips

Use a Spotting Scope, Even When Shooting a Scoped Rifle
A good spotting scope can “see” mirage much more clearly than even an expensive rifle scope. Take your spotting scope to the line and position it as sling shooters do, close enough to use without much movement. Focus the scope approximately 1/3 of the way down range or where the most significant wind effects are likely to occur. Take a quick look while waiting for pit service, glance at the flags and compare to your scope sight picture. I often see ambiguous indications at the target through the rifle scope, but see a clear indication of wind direction and speed through the spotting scope at the shorter distance. When shooting the Arizona Palma Championship at Ben Avery last weekend, I was scoring while the wind was coming from the east. Shooters up and down the line were out to the left, losing points. Mirage at the target looked moderate and the flags weren’t indicating strong wind. As I focused the spotting scope back, the mirage suddenly looked like it was flowing twice as fast around 500 yards than it was closer or farther. It wasn’t until I realized that the access road cut through the berm there that I understood what was happening. (Tip courtesy Gary Eliseo.)

Steven Blair F-Class Wind Tips

Don’t Over-React to Something That May Be an Anomaly
On ranges with sizable berms, a headwind or tailwind can cause significant elevation problems. It is generally not possible to see or predict when this will occur. When the conditions exist that cause elevation changes and other competitors are experiencing the same problem, the best strategy is to ignore it. Certainly, avoid shooting when the head or tail wind is gusting, the same as you would in a crosswind. But, if you react to random, range-induced elevation changes, the only likely result is to make it worse. Whether the problem is caused by range or ammunition, maintain your waterline hold until you have evidence that something has fundamentally changed.

Steven Blair F-Class Wind Tips

My .284 Shehane will usually require a click or two down during a string as the barrel warms. That is normal and manageable. But, if your shots are just bouncing up and down in the 10 ring, leave it alone. The same is also true of an occasional gust pushing a shot into the 9 ring. If the conditions have not changed and one shot just went out, it may be the result of a random occurrence that was not predictable. (Tip courtesy “School of Hard Knocks”.)

Adjust Spotting Scope Focus and Magnification as Needed to View Mirage vs. Target Details
In F-Class we only need to see mirage, spotters, and scoring disks. That does not take a lot of magnification. My scope is a Nikon 25-75x82mm ED. It is a superb scope for the money and makes it trivial to see minor variations in mirage. It is good to have the high magnification available, and it can always be reduced if necessary. I use different power settings for different situations.

Steven Blair F-Class Wind TipsSetting Magnification Levels
During a match, in very good viewing conditions, I set my spotting scope at 75X, full power. The mirage is more subtle in the morning and greater magnification is needed.

During a match with heavy mirage I set my spotting scope at about 40X. I have no problem seeing mirage, even at this magnification.

When practicing at 300 yards or closer I set my spotting scope at max power (75X) so I can see the little 6mm holes from my 6BR rifle. I usually need to focus back and forth between shots to see both bullet holes and mirage.

Steven Blair, 2012 California State Long Range F-Open Champion, has been shooting since childhood and competing for over 30 years. Before retiring, Steve spent 16 years in Engineering and IT with General Atomics. He has held Engineering and Marketing positions with several firearms companies and worked on projects from pistols to 155mm howitzers.

Permalink Competition, Shooting Skills 3 Comments »
August 30th, 2012

Mirage Shields Tame Barrel Heat for More Accurate Shooting

Even if you don’t shoot competitively, you can benefit from having a mirage shield on your barrel. The shield helps prevent barrel heat from “cooking” the air in front of your scope, which can distort the view you see through the optic. Barrel heat creates a mirage effect that can blur the target image and actually shift your apparent aiming point up and down. Competitors know that a mirage shield helps them shoot smaller groups and better scores. Mirage shields can likewise benefit Varmint shooters on those hot summer groundhog and prairie dog expeditions.

Make a Mirage Shield from Discarded X-Ray Film
Forum member Fabian from Germany, whose Sako 6BR was featured as a Gun of the Week, has devised a clever and inexpensive mirage band option. Fabian is a radiologist by trade. He notes that many X-ray machines require a daily test film for calibration. These are normally just discarded in the trash, so you can get them for free.

mirage shield

Fabian explains: “I’m a radiologist, so I handle medical x-ray films every day. Modern X-ray machines use laser-based printers and they need to print a test-film every day. One x-ray film is about 43×35 cm (16.9″ x 13.7″). Made from polyester, the films are very stable and only 0.007″ inches thick. They are light-weight, semi-transparent, and very stable. Using normal scissors, you can easily cut four mirage shields from a single sheet of film. Then glue on some velcro to attach to your barrel. Try it, you will not be disappointed.”

mirage shield

More Do-It-Yourself Ideas
Other forum members have made mirage shields out of common, inexpensive materials such as old venetian blinds, thin plastic edging strips, and even cardboard reinforced with strapping tape. There’s no “magic material”. However many shooters have found that wider shields (extending well past the barrel sides) work better than narrow shields, particularly in hot weather.

Mirage Shields with Printed Designs
If you prefer to purchase a mirage shield, Shotmaster 10X offers a wide variety of shields starting at just $5.00 for a plain white 18″ shield. Patterned shields (including camo designs) are priced by length: $8.50 (18″), $9.50 (20″), $11.00 (24″). All Shotmaster shields come with two (2) velcro patches with self-stick adhesive.

Shotmaster 10X Mirage Shield

Permalink Optics, Tech Tip 2 Comments »
May 18th, 2009

USAMU Teaches Wind-Reading on ShootingUSA May 20th

Mark your calendars for Wednesday, May 20th, when a “must-watch” episode of ShootingUSA television is broadcast. On the 20th, Sergeant Grant Singley and other members of the USAMU Service Rifle Team explain wind-reading for long range competition. This should be a very informative segment, enhanced with on-screen graphics illustrating key points.

Sgt. Singley notes: “A 5-mph crosswind at 600 yards will move an 80gr .223 bullet about 15 inches. You can see that being able to accurately read the wind will greatly enhance your success on the rifle range.” The USAMU uses a clock method to estimate wind value based on the direction. Then you add in the measured (or estimated) velocity for the vector value (wind strength and angle).

Sgt. Singley recommends the use of a wind meter, such as a Kestrel, to gauge wind speed. But observed conditions will also indicate wind velocity. Sgt. Singley explains: “Zero-to-three mph, is hardly felt on the shooters face, but smoke will drift. Three-to-five mph is felt lightly on the shooter’s face. Five-to-eight mph keeps leaves in constant movement. Eight-to-12 mph will blow dust and loose paper, and 12-to-15 mph winds cause small trees to sway.”

Using Mirage to Estimate Wind Speed and Direction
Long-range shooters also need to learn how to read mirage. Mirage is the reflection of light through layers of air that have a different temperature than the ground. These layers are blown through by the wind, and can be monitored through a spotting scope, to detect direction and speed. You can see what appear to be waves running across the screen. This is the mirage. The waves appear to be running right to left, which indicates a wind coming out of the right. To clearly see the mirage through a spotting scope, you bring the target into focus, then adjust the focus about a quarter turn counter-clockwise.”

Graphics copyright 2009 ShootingUSA, used with permission.

Permalink - Videos, Tech Tip No Comments »