By Jon R. Sundra
I can remember when looking through a state-of-the-art riflescope, all you saw was a simple crosshair of uniform thickness. No dual- or triple-thickness reticle arms, no stadia wires, no hash marks or circles, just a crosshair. I can even remember as a boy when scope adjustments had the horizontal and vertical wires moving independent of one another so that when the rifle was finally zeroed, the intersection of the reticle was often nowhere near the center of the optical axis!
We’ve come a long way since those days, and along the way we’ve seen various attempts to solve the problem of knowing where to hold when our target is beyond that distance at which our rifle is zeroed.
Knowing the various points of impact (POI) downrange and knowing where to hold is only half the problem; the other equally critical factor is knowing the distance to the target. So prior to the advent of compact and affordable laser rangefinders, it was a two-pronged problem.
If truth be told, for most hunters and most hunting situations, 300 yards is a very long shot, and within that distance the old Maximum Point Blank Range (MPBR) concept works pretty darn well. Even for the 106-year-old .30-06 cartridge shooting a 165-grain spitzer bullet, the MPBR is beyond 300 yards. In other words, even on an average-size white-tailed deer having a vital zone represented by a 10-inch circle, the aforementioned .30-06 load zeroed to impact dead-on at 284 yards (4 inches high at 100), will not rise or fall more than 5 inches from line of sight all the way out to 346 yards. That means that if your target is anywhere within that range, you can simply aim for the center the deer’s chest without having to worry about holdover or hold-under.
If a .30-06 could shoot that flat, imagine what the MPBR would be for, say, a .300 Winchester Magnum? Well, as much as one might assume there’d be a big difference, it’s not nearly as much as one would think. Consider: that same 165-grain bullet out of a .300 Win Mag zeroed at 308 yards (3.8 inches high at 100), would have a MPBR of 374 yards based on the same 10-inch vital zone. That’s only 28 more yards.
The earliest attempts at determining distance, hence the aiming point, for long shots used a stadiametric scope reticle whereby the space between the primary horizontal wire and a second wire below it subtended a known distance at a given magnification (the highest magnification in a variable power). If, for example, the distance between the two wires spanned 15 inches on a 200-yard target — the nominal chest depth of a white-tailed deer — at 100 yards it would span 7.5 inches, and 22.5 inches at 300 yards. So if the deer’s chest just fits between the wires, he’s 200 yards away. If its chest depth is two-thirds the span of the wires, he’s 300 yards, and so on. Trouble with the stadia system is that as the ranges increase, so does the margin of error. Still, given our abysmal ability to judge distances beyond 150 yards or so, it was better than pure guessing.
As stated earlier, the real breakthrough came with the compact and affordable laser rangefinder. No longer was determining distance to the target the problem. Now, all you have to do on those distant shots is hold over the required amount, given your known POI at that distance. Say you’re zeroed dead-on at 250 yards and you know your POI at 400 is 13 inches low. You simply hold that amount above your desired impact point … then get out your skinning knife.
That’s what I’ve been doing for more than 50 years, and it’s worked out very well for me, but then I’ve always tried to keep my shots under 400 yards. And now with laser rangefinders, the biggest variable has been taken out of the equation.
Still, there are plenty of hunters with limited field and/or shooting experience who would much rather have a specific aiming reference — dots or hash marks on the lower reticle arm — rather than having to guess how 18 inches of holdover looks like on a deer … or an antelope or elk, especially when that puts the reticle completely off the animal against a wooded background or an open sky.
One of the first to address the issue was the Burris people with their Ballistic Plex reticle. Their research revealed that the .243 100-grain, the .270 130- and 150-grain, and the .30-06 165- and 180-grain loads account from some 75 percent of hunting ammunition sales. They also found that the trajectories of the aforementioned were very similar out to 400 yards or more.
The solution was to come up with a nominal or average trajectory and use hash marks on the lower reticle arm to indicate the approximate POIs at 200, 300, 400 and 500 yards based on a 100-yard zero. For flatter-shooting magnums, a 200-yard zero is used, and the first hash mark indicates the 300-yard POI, the second one down 400 yards, and so on. It worked pretty darn well — enough that soon every scope manufacturer adopted similar reticles. In many respects, it wasn’t that much different from the mil dot system long used in tactical scopes, except that the mill dots are uniformly spaced and therefore do not relate to a specific trajectory.
Another way to accomplish the same thing — to provide a specific aiming reference for various distances downrange — was to calibrate the elevation adjustment knob to a nominal trajectory, and dial up the aiming point. This method needs nothing more than a conventional reticle; no need for hash marks.
Calibrating to a nominal trajectory isn’t precise, but it’s much better than guessing. Obviously, to work as intended, the scope adjustments must be accurate and repeatable. I’ve been on prairie rat shoots where some guys used dial-up exclusively; holdover was simply alien to them. My attitude is: Hey, whatever works for you! There’s no denying, however, that having a precise point on the reticle to place on the target has to be more accurate than guessing hold-over.
Fine tuning the dial-up approach was Nikon’s Java-run Spot On website introduced in 2010, which enabled one to input a specific Nikon BDC reticle-equipped scope and the ballistics of a specific load. If it was a factory load, that’s all that was required. With a handload, the caliber, bullet weight, ballistic coefficient and muzzle velocity had to be entered. In either case, the program spits out the exact range represented by the hash marks (circles in Nikon’s case). No longer were those circles (and the hash marks in between) merely approximations of POIs in 50-yard increments.
As an example, say we have a Nikon 2.5-10x50 with BDC reticle and we’re shooting a 7mm WSM 140-grain Winchester Ballistic Silvertip factory load at 3,225 fps. Going to the Nikon website, we enter a sighting-in distance of 100 yards, with a desired zero range of 250 yards (you’re given a choice from 50 yards to 300 in 50-yard increments).
A click of the mouse tells us to zero 2.1 inches high at 100 yards to print dead-on at 250 using the primary reticle intersection. The first circle on the reticle arm below is shown to represent bullet impact at 345 yards, the one below that 450 yards, the one below that 540. To fine tune it even further, you can enter the anticipated altitude, humidity, atmospheric pressure where you’ll be hunting, along with crosswind velocity and up- and downhill shooting angles, and they will be computed as well. Naturally, one must remember the various values and then guess a little if the critter is in between those distances, but those hash marks between the circles make that easy.
This year, Nikon has brought its Spot On program even further along with what just might be the best answer yet for accurate long-range shooting. For $99.95, Nikon will furnish an elevation knob custom calibrated to a specific trajectory, so you can simply dial the distance and hold dead on at any range. You just go to www.nikonhunting.com and it’ll take you to the Custom Turret program.
Step 1 is selecting your exact model Nikon scope; all of them are listed — Buckmasters, Coyote, Monarch, etc.
Step 2 is to select your cartridge and load. Assuming you’re using factory ammo, once you select the load, the program automatically enters the muzzle velocity and ballistic coefficient. If a handload, you must enter the bullet weight, MV and BC.
Step 3 asks for your desired zero range from 50 to 300 yards in 50-yard increments, and the sight height above the bore. Step 4 allows you to change the already filled-in standard values for altitude, temperature, humidity and barometric pressure if you so choose.
And lastly, Step 5 asks you to select which style elevation turret you want — the low-profile hunting scope type, or the taller target style. That’s all there is to it.
To check out this latest refinement of the Spot On program, I ordered a custom turret for a Nikon Monarch 3-12x42 scope I had on hand, specifying the same load I used as an example earlier — the Winchester Supreme 140-grain Ballistic Silvertip load in 7mm WSM caliber. Ten days later the turret arrived, but it was calibrated for a 200- rather than a 250-yard zero. Oh well, no big thing.
The rifle I used for this experiment was an H-S Precision Pro-Series SPL (for Sporter Lightweight). This is the same rifle I used on my ibex hunt in Kyrgyzstan back in ’08. It’s one of the most accurate rifles I own and it absolutely loves the Winchester Supreme 140-grain Balllistic Silvertip load. I figured I’d use the regular turret to zero-in the gun as I normally do. But with the Spot On turret calibrated for a 200-yard zero, the program now told me to zero in 1.2 inches high at 100 yards rather than 2.1 inches. Once zeroed-in, I figured that all I should have to do is replace the original turret with the Spot On one, and index it at the “200” setting. It worked like a charm.
Unfortunately, my club range is only 300 yards, so I was only able to check it out to that distance. Like the program’s name, the gun was indeed Spot On at each distance. I dialed and fired three shots at 200 and 300 yards, then back down to 200, then back up to 300. Each instance, the average POI was within an inch or so of center. There is no “100” setting, but being zeroed only 1.2 inches high at the 200 setting, you don’t need it. Based on its accuracy at 300 yards, I have no doubt that at 400 yards, and probably 500, hitting a deer-size or larger target would not be a problem; all you need is a dead-steady rest and a laser rangefinder.
I also like the fact that with the Spot On turret you’re moving the reticle, so you can use a conventional crosshair instead of having those distracting hash marks or circles in the field of view. For me, it comes full circle, because when I look through this high tech Nikon scope, all I see is a crosshair, just like I’ve been using for more than a half century!