A RIFLEMAN’S OPTICS
Even for someone taken aback by the rows of puzzling buttons on a television remote, SIG Sauer’s Ballistic Data Xchange (BDX) Technology is easy to use. I was able to download the SIG BDX app to my iPhone to configure bullet ballistic profiles, transfer that information to a SIG KILO BDX rangefinder, and then to a SIG SIERRA3BDX riflescope that displayed an illuminated aiming dot that compensates for bullet drop and drift out to 800 yards.
The BDX system uses a Bluetooth connection to send ballistic data collected with an Applied Ballistics Ultralight (ABU) ballistic calculator. Hundreds of different rifle bullets are listed on the BDX app, and ballistic profiles for up to 25 bullets can be stored in the free app and synchronized to a BDX rangefinder. With one profile active in the rangefinder, a distance reading can be taken, and a moment later, elevation and wind-hold information is displayed to compensate for the bullet’s drop and drift at that distance. A KILO rangefinder can also be used as a standalone unit. The KILO2400BDX ranges reflective objects up to 3,400 yards, trees up to 1,800 yards and deer to 1,400 yards.
I took the next step and linked a KILO2400BDX to a SIG SIERRA3BDX 4.5-14x 44mm scope on a Weatherby Mark V Altitude .257 Weatherby Magnum. To shoot the .257, I hand loaded Nosler 115-grain Ballistic Tips with 69.0 grains of IMR-7828ssc powder. That combination resulted in an average bullet velocity of 3,348 fps as measured 10 feet in front of the Weatherby’s 26-inch barrel. To create a bullet profile on the BDX app, I entered the Ballistic Tip bullet, its muzzle velocity and zero range of 100 yards. Only a G1 ballistic co-efficient (BC) was available for the bullet, but the app automatically figured a G7 BC.
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March - April 2019