Hello channel fans and family, and welcome to Slav Guns. A 1911 is a 1911 and an AK-47 is an AK-47, whether it was built in the 1960s or last year. Guns themselves have not changed much, but technology has made parts of the shooting experience a lot better, and optics are a category that was ripe for it. This one is my introduction to the Sig Sauer BDX (Ballistic Data Xchange) system: a BDX riflescope and a Kilo rangefinder that talk to each other, so you can range a target and get your holdover lit up right in the reticle.
Disclosure: Sig Sauer provided the scope and rangefinder for testing and evaluation, and Ruger provided the Kestrel 5700. No compensation was received, and neither company saw the video before it was published.
Quick context: this video is from late 2019 and was part one of my BDX series. It covers the original Sierra3 BDX and Kilo BDX lineup, and the prices below are what was listed then. Sig has updated the system since; for the newer gear, see my Sig Sauer BDX 2.0 first look.
TL;DR
- What it is: A Sig BDX riflescope plus a BDX-compatible Kilo rangefinder, paired over Bluetooth. You range the target, and the scope’s reticle lights up the elevation and windage hold for you. You don’t have to dial or check a ballistic app.
- My kit: The BDX Kilo2400 combo: Sierra3 BDX 6.5-20×52 scope plus Kilo2400 BDX rangefinder, mounted on my Ruger Hawkeye Long Range Target in 6.5 PRC.
- Lineup at the time: Scopes in 2.5-8, 4.5-14, and 6.5-20 magnification. BDX rangefinders: Kilo1000, 1400, 1600, 2200, and 2400. Combo kits ran about $600 to $1,700 MSRP, and street prices were well below that.
- Brain: The rangefinder runs the Applied Ballistics Ultralight engine, which is capped at 800 yards.
- Going past 800: Add a Kestrel 5700 with LiNK or a Garmin Foretrex. Both run Applied Ballistics Elite, which is good for solutions past 4,000 yards.
- Best for: Hunters, without question. New precision shooters too, but watch out for it becoming a crutch.
The old way vs. the BDX way
A typical long-range process goes like this. Zero your rifle at a known distance, usually 100 yards or meters, and know roughly what velocity your ammo makes. A chronograph isn’t required, but it helps a lot. At the range, you first need the distance. Sometimes it’s posted, and sometimes it isn’t. A deer won’t stand next to a distance marker and wait for you. You can estimate with the reticle, or do what the cool kids do and use a laser rangefinder.
Next you need a firing solution. The old school has their dope memorized, traditionalists use a range card, the cool kids run a ballistic app on their phone, and the rich capitalist pigs use a Kestrel. Then you either dial the turrets or hold over in the reticle. If your inputs are right (muzzle velocity, distance, and environment), you should hit. It’s just physics.
BDC reticles with printed lines or dots for specific distances try to shortcut that. The catch is that they’re built for generic calibers and loads, not your rifle and your ammo. Up close that may be fine, but at long range those dots turn into a guesstimate.
BDX skips the middle steps. Once your rifle is zeroed and you know your velocity, you range the target with the Kilo, and the firing solution goes straight to the BDX scope. The reticle lights up the right dot for elevation and windage. You don’t touch a ballistic calculator or dial anything. Range, aim, pull the trigger.
Pick one from column A, one from column B
Think of it like the specials menu at a Chinese restaurant. Column A is a Sig BDX riflescope, and column B is a compatible Kilo rangefinder. You can buy each piece separately or get a combo kit with both. I’m running the BDX Kilo2400 kit, which pairs the Sierra3 6.5-20×52 with the Kilo2400.
How setup works
Everything gets set up in the Sig BDX app. That’s where you enter your rifle and load details. The app sends that profile to the rangefinder and bonds the rangefinder to the scope. After that, you don’t need your phone unless you want to change shooting profiles. I’ll do a full app walkthrough in a separate video.
At the range, everything starts with the rangefinder. It finds the range (duh), and it also works as the ballistic calculator. Using the Applied Ballistics Ultralight engine and the profile you loaded, it works out the solution and sends it to the scope over Bluetooth. Then the reticle lights up your hold for drop and wind.
The reticle: “digital focal plane”
A quick refresher: in a first focal plane scope, the reticle grows and shrinks with magnification. In a second focal plane scope, it stays the same size. Sig calls the Sierra3 BDX a hybrid, or digital focal plane. The reticle is technically second focal plane and stays the same size, but the lit BDX holds adjust automatically as you change magnification.
The trade-off is line thickness. The reticle has to fit those illuminated dots, so it runs on the thick side for a second focal plane scope, and that’s the most common complaint you’ll hear about this scope. I understand why, but the more I used it, the less it bothered me. The top half of the reticle is mostly empty, which leaves plenty of room to spot hits.
Who it’s for
Hunters: For hunters, it’s a no-brainer. Full disclosure, I’m not a hunter, but you don’t need to be a chef to know steak comes from cows. A hunter isn’t shooting at a stationary target from a fixed bench. The animal could be anywhere, at any distance. Inside about 200 yards the ballistics barely matter, but at the longer distances common out West, being able to range and immediately see your hold is huge.
New precision shooters: This is where my feelings are mixed. The first time I really used the system was at a range I’d never shot before, with no posted distances. I ranged the steel and went one shot, one hit from 100 to 700 yards by ranging, holding the lit dot, and pressing the trigger. It’s the Staples Easy Button of precision shooting. A few folks at the range who were paying for a long-range class were seriously impressed.
That ease is also the problem. It’s so easy to shoot long range that when something doesn’t work and you have to dial for yourself, you can get lost. It’s a great way to introduce new shooters to long range, but it can easily become a crutch.
Limitations I ran into
- Weather: On my one trip to extended long range, it kept switching between torrential rain and snow. In those conditions the rangefinder struggled to get a clean return past roughly 600 yards. To be fair, 95% of gun owners won’t be out shooting in that, and it was snowing pretty hard. When that happens, you can switch the scope to work as a regular BDC reticle at known distances, as long as you know your velocity and the wind.
- 800-yard cap: The Applied Ballistics Ultralight engine in the app and rangefinder stops at 800 yards. If you range something farther, the system tells you it’s out of range.
Breaking 800 yards with a Kestrel
This is where being a rich capitalist pig pays off. Add a Kestrel 5700 with LiNK or a Garmin Foretrex. Both run the Applied Ballistics Elite engine, which gives you solutions past 4,000 yards. Thanks to my friends at Ruger, I paired the Ruger Kestrel 5700 with the rangefinder and shot past 800 yards.
Here’s how it works. Pair the Kestrel with the rangefinder and switch the rangefinder to its Applied Ballistics Elite mode. Now when you range a target, the rangefinder sends the distance to the Kestrel instead of solving it on board. The Kestrel factors in the weather, runs the Elite engine, and sends the solution back to the rangefinder, which passes it to the scope. It all happens fast, and you don’t enter anything. Getting past 800 yards was my big question going in, and with the Kestrel it worked brilliantly. Technology is awesome.
Bottom line
The Sig BDX system takes ranging, solving, and holding and turns them into one step: range, see the dot, shoot. For hunters at real distances, it’s an easy recommendation. For new precision shooters, it’s a fantastic on-ramp, as long as you still learn to dial on your own. The 800-yard limit of the built-in engine is real, but a Kestrel 5700 or Garmin Foretrex removes it. Deeper dives on the scope and the rangefinder are coming in future videos.
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Would you trust a scope that lights up your holdover, or are you a dial-it-yourself shooter? Drop it in the comments.
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