Though it sounds complex at first, the Sig BDX system is simply a smartphone, rangefinder and riflescope combination that calculates holdover. The rest is up to you.

How the Sig BDX system is changing shooting:

  • Sig BDX smartphone app programmable for a number of rifles and loads.
  • Kilo rangefinder provides app the ballistic and environment input.
  • Sierra3 rifle scope presents the holdover in an illuminated dot.
  • System calculates real-time and alerts if a new holdover has been calculated.
  • Anti-cant system adjusts to rifle’s angle.
  • App alerts shooter if potential shot is out of range.

On May 3 of this year, I entered a conference hall in Dallas on the eve of the 2018 NRA Annual Convention and Meetings under the promise of not disclosing what I was about to see until the embargo was officially lifted at 9 am the following morning — at the open of the show. The curtain lifted, jaws dropped — and I’ve been fielding questions from readers and friends alike ever since.

SIG-BDX-3

Behind that curtain was the new Sig BDX (Ballistic Data Xchange) System, a cutting edge collaboration of rangefinder, riflescope and smartphone that makes holdover calculations so bulletproof that it almost seems unfathomable. I hate the phrase “game changer,” but if ever there was a category-revolutionizing product worthy of that moniker, this very well seems to be it.

Similar products are have been on the market for quite a while now, but each has its drawbacks. The Burris Eliminator is a great rangefinding riflescope, but it does kinda look like you’ve got a couch strapped to your rifle by the time you’re all done. And it’s arguable that no one makes a better rangefinding riflescope than Swarovski, but I could buy a pretty solid winter beater car for about the same cost.

While no product in this category is truly perfect — we are dealing with aiming solutions that involve batteries — the Sig BDX system seems to have the edge in just about every facet of the technology, and that includes price. I say “seems” because, well … this system is that new. Though the introduction was made in early May, product is now just becoming available. And because Sig has designed this beast to be a hunter’s new best friend, you need this information now to properly determine if this is an optical pool into which you want to dip your toe.


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Sig is calling the reticle around which this system revolves the “BDX-R1 Digital Ballistic Reticle,” claiming that this entire setup is capable of providing a ballistic solution out to 8000 yards with 1 MOA of accuracy. That’s bold. But — if you’ve used ballistic apps before, you should already know the “garbage in, garbage out” mantra: The information this system provides is only as good as the information you put into it.

So, let’s break this BDX System down, piece by piece, and have an in-depth look at what makes the Sig BDX System tick because it seems pretty intense at first glance. However, although the technology that goes into this system far extends the reach of my cognitive grasp, the user interface is very straight forward, and that’s what matters.

The Brains

Sig-scope

You already own the brains of the BDX System: your smartphone. Through either Google Play or the App Store, down load the “Sig BDX” app for whatever you’re packing, Android or iPhone, and create a profile much like you would on Facebook — except for your rifle: Luke’s Creedmoor, Big John … heck, maybe you’ve got a gun named “Battle Axe” after your wife (may I suggest password protecting your phone?).

The app allows for profile creation to match a handful of your rifles, and it’ll ask you all the basics — caliber, manufacturer, bullet, ballistic model — and even a few intimate details to make sure it knows your gun inside and out. Remember: This is the brain that feeds the entire system the necessary data.

If you’ve previously worked at all with a ballistic app, this is going to be old hat. And once you’re in the field, you can update the Sig BDX app with environmental conditions, including altitude, temperature, wind speed and wind direction. The more you can help BDX, the more BDX can help you in return. Precision is the name of the game here.

Via Bluetooth, exactly like when your phone tells your truck what songs to play through the speakers, the BDX app uses your smartphone to translate all your rifle’s ballistic information (remember what you shared with your app about the Battle Axe?) with the rangefinder.

The Translator

SIG-BDX-5

The Kilo rangefinder is the middle man in this system. It takes your rifle’s ballistic information and the environmental information you input into the app, and it cross-references all that with real-time range readings — and then translates and feeds that info to the riflescope.

At present, there are four Kilos in the BDX system: 1400, 1800, 2200 and 2400 — starting at $299.99. The Kilo2400BDX also features built-in environmental-reading capabilities.

Once your phone and the rangefinder are paired, the Kilo operates exactly as any other rangefinder does: Press a button to get the digital display to wake up and then press away to range to your heart’s desire — it’s talking to your riflescope via Bluetooth the entire time.

The Eyes

SIG-BDX-1

There are currently four Sierra3 riflescopes compatible with the BDX system: 3.5-10x42mm, 4.5-14x44mm, 4.5-14x50mm and 6.5-20x52mm — with prices starting at $599.99.

On the outside, the Sierra3 looks like most any other riflescope — almost. On the magnification adjustment ring, there’s a small blue light that indicates when the rangefinder has locked a range and successfully transmitted that information to the Sierra3.

Everything up to this point — the profile information uploaded to the app, the environmental data, the range provided by the Kilo rangefinder — everything has been a building block to make sure that when you look into the scope and prepare to pull the trigger, the correct holdover dot in the reticle is exactly where it should be. Place the yellow dot where you want the bullet to impact and go to work.

Peace Of Mind

SIG-BDX-10

There’s a lot going on in this system that must fall into the trust category. The beauty of this system is that you’re allowing it to completely calculate your hold point. The scary part of this system is that you’re allowing it to completely calculate your hold point.

When the Sierra3 is searching for data from the rangefinder, the blue indicator light on the magnification ring flashes slowly. When the data had been locked, the blue light glows solid. And because things can happen quickly, the light flashes quickly when there’s new holdover dot update from the rangefinder. Think of it as your riflescope letting you know what it’s thinking through Morse code. There still needs to be trust that everything is going to work and that trust must come through range time, but that little blue indicator light is a nice visual addition to affirm that all the guts are working correctly.

Just A Riflescope

SIG-BDX-7

Minus the blue indicator light (which is not really noticeable then the scope is off), the Sierra3BDX riflescopes look and operate like any other “traditional” riflescope. Each wears HD glass, a 30mm maintube, side-focus parallax adjustments and Sig’s LevelPlex digital anti-cant system. And when the system is shut down, the reticle looks like any other duplex configuration.

Changing Winds

There’s no doubt the entire BDX System is going to rattle a few cages. Sig knows this. And, quite frankly, it took me a bit of thought to settle on the moral conclusion that this entire system is set up to force the shooter to do more work on the front end though data input so that there’s less room for computation errors on the back end — during the shot.

Editor’s Note: This article originally appeared in the August 2018 issue of Gun Digest the Magazine.


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