Mirage Shields — Not Just for Benchresters Anymore

Mirage 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 $4.50. Shotmaster 10X offers a variety of Patterned Mirage Shields, starting at $6.00. These include a Patriotic theme and even Tiger Stripes:

NEW 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.

At the request of AccurateShooter.com, Shotmaster 10X has just introduced a new 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 (20″ are $9.50; 24″ are $11.50).

Monitor Barrel Temps with Heat-Sensitive Strips

Bad things can happen if your barrel gets too hot. First, with some barrels, the point of impact (POI) will shift or “walk” as the barrel heats up excessively. Second, even if the POI doesn’t change, the groups can open up dramatically when the barrel gets too hot. Third, if the barrel is very hot, the chamber will transfer heat to your loaded cartridge, which can lead to pressure issues. Finally, hot barrels wear out faster. This is a very real concern, particularly for varmint shooters who may shoot hundreds of rounds in a day. For this reason, many varminters switch among various guns, never letting a particular barrel get too hot.

How do you monitor your barrel temperature other than guessing by “feel”? BAR-L Benchrest strips visually display heat readings from 86 to 140 degrees. Think of these strips as compact, unbreakable thermometers. With adhesive backing, they can also be used to monitor barrel heating. Put a strip on the side of the barrel and the barrel’s temp will be indicated by a stripe that changes from black to green. There is also a “general purpose” strip that reads to 196 degrees (bottom row). The Benchrest strip (86F to 140F) is in the middle.

Value-Priced Temp Strip 10-packs
If you have many rifles, McMaster.com (a large industrial supply house) offers the same reversible, 7 temperature, 86F to 140F strip (item 59535K13) for $11.86 per pack of ten (10) strips. That’s an excellent value. Thanks to reader Josh B. for this tip!

Another source for BAR-L Temp Strips is Neconos.com. This vendor offers Bar-L temp strips for $9.00, or $25.00 for a 3-pack.

Controlling Ammo Temperature is Important Too
Keeping your loaded cases at a controlled temperature is vital for maintaining good ES and case life. At a late summer varmint match we observed pressure signs with cases that had been sitting in direct sunlight for about 15 minutes. As we were running a “moderate” RL15 load, the pressure indications were surprising. Testing over a chronograph, cases that had been sitting in direct sunlight showed velocities up to 70 fps higher than those that had been kept in the shade. Using QuickLoad’s temperature function, we calculated from the rise in velocities that case pressures had increased by over 4,000 psi–just from 15-20 minutes in direct sunlight!