October 10th, 2007

Oversize Mirage Shield Works Well

Past NBRSA 1000-yard Champion Jerry Tierney has been experimenting with a “super-sized” mirage shield. Like other shooters, Jerry noticed that mirage produced by barrel heat was creating optical distortions, causing groups to open up on the target. He had fitted a conventional, narrow, venetian-blind style mirage band to his barrel using velcro fasteners. This had the expected beneficial effect, until Jerry’s round count rose to the point that the barrel heat was overcoming the narrow band’s shielding effect.

Jerry figured “if a narrow band is good, maybe a wide mirage band is even better”. Jerry experimented with materials and sizes, eventually settling on a 4-inch wide section of cardboard running from the scope foreward. He wrapped the cardboard with plastic strapping tape to add stiffness, and then, during his experiments, zip-tied the cardboard to the barrel. The venetian blind band was then placed on top of the cardboard. This gives him a two-tier mirage shield.

Tierney barrel Mirage Shield

To Jerry’s surprise, with the jumbo mirage shield in place, the barrel remained accurate for a much longer round count. Jerry told us: “I thought the barrel was ‘going off’ as it heated up. But what I found, by using the big shield, was that the barrel stayed accurate even when it was hot. The barrel actually continued to shoot very well when hot–once I started using the bigger mirage shield. Mirage was causing the accuracy problems. With the big shield in place, I can put more rounds through the tube without seeing negative effects on the target. I concluded that this gun can shoot well with a hot barrel, so long as I kept the mirage under control. I know the cardboard shield looks funky, but it works. I can shoot longer strings without losing accuracy.”

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