December 28, 2022
Seven caribou bulls fed across the bench below, nipping lichen and tundra grasses in their fast-paced feeding walk. Intermittent curtains of rain shielded them, alternating with alder thickets just tall enough to hide vitals. One bull was a sure-enough shooter; not a monster but a great bull for a DIY, drop-camp solo hunter.
I lay prone in the soggy rocks atop the ridge, crosshairs trailing the bachelor herd. Misty rain came in waves, complicating everything. My rangefinder only worked when the rain curtain thinned. My scope lenses shimmered with water. And every surface was cold and slippery.
Before I managed to get off a shot, the bulls dropped into a massive gully and vanished, quartering obliquely away.
Never, they say, try to catch up with a caribou moving away from you. I leapt up, grabbed my rifle and tried anyway, dashing down the length of the ridge as fast as I could scramble through the wet rocks. Dropping 50 yards to a tiny flat bench the size of a picnic table, I flattened back into the soggy, rock-studded earth, prone and ready just as the caribou bulls emerged from the far side of the gully.
A momentary break in the rain allowed me to pick out the big bull. My rangefinder read 611 yards. Far, any time. Really far, when solo in Alaska.
My Browning X-Bolt in 6.8 Western was topped with a 4.5-14x40 Leupold VX-3HD scope with CDS-ZL turret. I’d sent the custom turret voucher included with my scope to Leupold and had a CDS (Custom Dial System) turret engraved to match the ballistics of my rifle.
It was now or never. The shot was long, but I had the rifle, the cartridge, the scope, and the custom ballistic turret to get the job done. Wind was nil, and the curtain of rain had abated. I dialed the CDS turret a click past the 600-yard mark. Holding on the vitals, I heaved a breath, exhaled, and squeezed the trigger.
Thanks to the 6.8 Western’s moderate recoil, the muzzle brake, and my sturdy position, I was able to spot my own impact. Hit low, down near the brisket but inside the thoracic cavity, the bull lurched and trotted a few steps. Paused. Holding a few inches higher, I sent another 165- grain AccuBond Long Range. Mist sprayed from the center of the bull’s shoulder. He wobbled and died.
As rain closed back in, I wryly noticed that the bull had dropped near the head of a brush-choked, sheltered gully that swept far down into the timbered, creek-laced country below. Just the sort of location that a savvy old grizzly might pick to wait out a soaking rain. And I’d seen no less than five grizzlies the day before.
Before moving, I dialed the CDS turret back down to the zero stop, where the zero lock automatically engaged. Bears I wished none of, but in case need arose, the crosshairs were dialed back down for a dead-on hold on anything out to 250 yards.
Leupold includes a voucher for a CDS turret cap with a variety of hunting scope models. Specifically, the Freedom, VX-3HD, VX-5HD, and VX-6HD lines with dial-up turrets. (Additional CDS turrets may be ordered for $80.)
Engraved to match your specific rifle’s ballistics, the CDS cap enables you to dial the turret for range, hold where you want to hit, and fire.
To order, get online at leupold.com/custom-dial-system and fill in the required info. This includes cartridge; bullet type, weight, and ballistic coefficient; muzzle velocity; and sight-in “zero” distance.
Muzzle velocity is a critical component. While you can input the advertised numbers from your box of ammo, they’re almost always different than what your gun will actually generate. You’re best served checking the load in your rifle with a chronograph, so you can supply Leupold with an exact muzzle velocity.
You’ll also provide the average temperature and altitude at which you hunt. This enables Leupold to accurately calculate and compensate for air density and its effect on bullet flight.
Sight height is required and is measured from the center of the barrel to the center of the scope’s main tube. This is not an exact science; just lay a measuring tape against the side of your rifle and get as close as you can.
Another critical piece of the puzzle is zero distance. Unless you’re shooting something rather ponderous, such as a .45-70 or a .30-30, you’re best served with a 200-yard zero. That way, you’ll hit just an inch or two high at 100 yards and depending on cartridge only 6 to 10 inches low at 300 yards.
Armed with your info, Leupold’s techs put a blank turret cap into the laser engraver, input the parameters, and the machine engraves numbers (representing 100-yard increments) around the circumference of the turret.
A few weeks after submitting the info, you’ll receive a crisp new CDS turret in the mail. Install it on your scope, refine your sight-in to perfection at your chosen zero distance, and you’re ready to begin reaching out.
Trust, But Verify
Modern ballistic calculators have wizard-like ability to predict bullet flight, and Leupold’s engineers are top-notch at converting ballistic predictions into hardware. You’ll almost certainly find that your turret’s dial-up matches your bullet drop.
Still, it’s good practice to validate. Stretching your rifle out proves the system and builds confidence. Plus, who doesn’t want another excuse to get out and shoot?
Hunters in the West can usually find a long-distance range or appropriate public land within an hour’s drive. Easterners, Southerners, Midwesterners—basically anybody that lives in flat, wooded areas—may have to drive farther to shoot long. It’s worth the trip.
Range setups ideal for trajectory validation have steel targets set from 200 yards to at least 600 yards. With your 200-yard zero point of impact (POI) refined and confirmed, dial up and work your way out.
Be sure you dust off your best shooting skills. Small human errors can cause a considerable POI shift way downrange. And big errors such as a flinch? You may not even come close to the target. Put on your big-boy pants and shoot well, because to validate that shiny new CDS turret, you’ve got to send those bullets true.
If you find you’re trending slightly high or low as distances stretch, it’s most likely caused by a slightly imperfect zero. To correct it, shoot at a downrange target an exact distance away—let’s say 400 yards. Adjust your dial and keep shooting until you’re hitting exactly where the crosshairs are when the trigger releases.
Once satisfied, loosen the set screws that hold the CDS turret cap in place and rotate it until the number 4 is lined up with the reference mark on the turret. Now, the dial’s yardage numbers match the point of impact way downrange—where it’s most critical.
Depending on the cost and quality tier of the scope model you purchase, CDS dial-up turrets have a range of features. Custom dials for the entry-level Freedom line are simplest, but they do have a zero stop (which the standard MOA dials that come on the scope lack). These are affordable scopes—and darned good ones. Each full rotation of the turret moves the crosshairs 15 minutes of angle (MOA).
Next in the CDS lineup are those with a CDS-ZL designation. Like the less expensive versions, they move the crosshairs 15 MOA per rotation. These are found on the VX-3HD line, and feature a zero stop, and a zero lock.
The zero stop is a resettable, hard wall you dial down to after shooting long. No need to even look; just crank that dial down until it stops. This stop is a consistent reference and protects you from accidentally leaving your turret one full rotation off from zero.
The second feature—the ZL—is nearly as awesome. An inner lock engages when the turret is returned to zero. This prevents the turret from being accidentally rotated when the rifle is slid across a truck seat or into a saddle scabbard. A small silver button at the rear of the CDS turret must be depressed before rotating the turret. It falls naturally beneath the thumb, and functions intuitively.
There’s only one down-side to the CDS-ZL: It can only be turned one full rotation upward. Still, with modern cartridges and projectiles, that’s enough to dial to 700 yards or more—which is farther than most hunters should be shooting.
At the top of Leupold’s line is the CDS-ZL2. It is found only on the VX-5HD and VX-6HD scopes. It’s slightly bigger in diameter. Each rotation moves the crosshairs 20 MOA. Best yet, it offers two full upward rotations. Like it’s little brother, a small silver button must be depressed to unlock the turret. The button remains flush with the outside of the turret through the first rotation. As the turret transitions to the second rotation, the button sinks below the surface, providing a visual and tactile cue that you’re dialed up into the second rotation.
Extreme-range precision shooters sometimes argue against turret dials engraved with yards, suggesting that environmental changes in temperature, altitude, and angle introduce discrepancies that an engraved turret can’t compensate for. It’s better, they say, to use a turret with an MOA or Mil scale, and use a ballistic solution crunched with real-time atmospherics.
For extreme range, they’re correct. However, that process is slow.
For hard-hunting guys and gals shooting inside 600 yards or so, nothing beats a turret marked with yards. There’s no digging out electronics, firing up apps, taking atmospheric readings, and slowly assembling all the pieces of the puzzle.
For practical hunting to 600 yards, I’ll even argue against cutting-edge smart optics with environmental sensors and on-board ballistic calculators. This is particularly true on moving game: for example, a rutting bull elk constantly prowling around his harem. With smart rangefinders, one must continually transition from rangefinder to scope to rangefinder and back again. With a CDS, a buddy can just provide simple range updates. The turret can be adjusted as needed.
Big bucks and bulls rarely provide relaxed, long windows of opportunity. With Leupold’s CDS on board, you just range, dial, and shoot when the moment of truth arrives.