An annual question at shooting ranges around the country is “What distance should I zero for?” And the answer is…
The distance that gives you the most flexibility for putting your bullet on target quickly with minimum measuring, guessing, hoping, or missing.
And that’s rarely 100 yards.
The 100 Yard Problem
The old 100-yard zero is perfect if your longest shooting distance isn’t much beyond that. Otherwise a 100-yard zero wastes your bullet’s trajectory potential. By 200 yards you’re already needing to compensate for bullet drop. To understand this, let’s look at a trajectory that is considered “flat.”
I don’t know what you imagine when you hear cartridge XYZ shoots “flat,” but when I was a new shooter I assumed it meant the bullet went like a laser to 300 yards or so. That’s flat! But it’s also impossible. Bullets are not light waves. Gravity begins to pull bullets down the instant they leave the muzzle. If you aimed a barrel perfectly in line with a target 100 yards away with the world’s highest B.C. rating at 4,200 fps, it would miss. Oh, it would be close, but it would still fall under the precise point of aim by about an inch.
An inch is no big deal even if you’re shooting squirrels in the head. But at 150 yards this hyper-velocity bullet would already be down by 2.3 inches. At 200 yards it would be low by 4 inches. Gravity is relentless. Meanwhile, back in our real world where most of us shoot “flat shooting” rifles like .243 Win., .270 Win., 7mm Rem. Mag., and the more recent 6mm Creedmoor, 27 Nosler, and 7mm Remington Ultra Magnum, the drops are even greater. We won’t even bother with the .30/30 or .45/70.
Setting the Angle
To compensate for the gravity of this situation, we routinely cant our muzzles at a slight upward angle from our line-of-sight. You can see this by how high open sights perch above bores. The higher the rear sight in relation to the front post, the more the muzzle gets angled up. With scopes perched 1.5 to 2 inches above bores, it’s obvious we must angle muzzles upward to cross their line-of-sight. We adjust reticles so that our canted barrels drop our bullets where the sights are looking at specific distances, usually 100 to 200 yards, but sometimes as far as 300 yards. The longer the spot-on range, the steeper the angle of the barrel cant.
Extreme range shooters know all this because they often put 20 MOA rails under their scopes. That results in their barrels pointing above their targets at a huge angle, yet they can dial turrets to drop their bullets right on target at 100 yards, 800 yards, even 1,500 yards.
For mere deer and elk hunters at hunting ranges, barrels are usually canted so that the bullet first passes through the sight line at about 30 yards. It is then flying above line-of-sight, but not because bullets rise as they travel downrange. They fall. Always fall. But because we shoot them upward, they are like baseballs flying in from the outfield. They arc up so they go farther before hitting the ground.
How High Can They Fly?
So just how high are we throwing these bullets? It depends on how far downrange our target stands. If we want to hit a target at 300 yards, we have to angle that muzzle a lot more than we would to hit at 100 yards. And to hit 1,000 yards? Hang onto your seat: if we fire a high B.C. bullet from a .308 Winchester 2,800 fps, we’d have to aim 369 inches above a 1,000-yard target to drop our bullet on it. That’s 30.75 feet of drop.
At a more common, reasonable hunting range of 300 yards that drop would “only” be about 23 inches. Meaning if you aimed a foot over the deer’s back, you might hit it in the heart.
Flattening the Highs and Lows
Minimizing big drops like this is why cartridge designers invented magnums. Adding speed to that 168-grain bullet makes it go farther before it drops too far. So let’s do that. Let’s stuff that same bullet in a .300 Remington Ultra Magnum and push it 3,400 fps. At this speed our 1,000-yard-drop would be 20 feet. At 300 yards our hyper-velocity, flat-shooting super magnum would plummet 15.3 inches.
So why not crank up muzzle velocity even more? Pressure, man, pressure. Brass cases can only withstand so much pressure. When thickened to handle increased pressures, steel barrels become too heavy and bulky for comfortable carry. Sig Sauer has come out with a steel headed cartridge (277 Fury) and a rifle engineered to handle about 15,000 more psi than current highest pressure cartridges, but it has limits, too. And gravity will eventually pull those faster bullets to the ground.
Somewhat depressing, isn’t it? But such is life on Earth where gravity is a constant. But that’s not all bad because we can work around a constant. Unlike the wind that changes and deflects our bullets thither and yon, good old gravity just keeps on tugging at 32 feet per second. Use that constant with the known muzzle velocity and the weight/shape/diameter of your bullet (collectively rated as its B.C.) and we can accurately predict drops at all distances (aside from changing atmospheric conditions like barometric pressure, temperature, and humidity.)
Read Next: How to Really Zero Your Rifle
Tricks for Extending Range
To increase a rifle’s effective range and decrease bullet drop you need to increase the muzzle velocity, increase bullet B.C., and increase your zero distance.
Everyone understands the benefit of faster muzzle velocity. The bullet goes faster, thus farther before gravity pulls it to ground. B.C. is a bit more mysterious. It works through aerodynamic efficiency. The higher the bullet’s B.C. rating, the better it resists air drag. This in turn helps it maintain more of the muzzle velocity it started with. This is why some relatively slow cartridges like 6.5 Creedmoor can sometimes shoot flatter than faster rounds like the .300 Win. Mag. beyond 600 yards because the 6.5 is inherently a low-drag cartridge and will retain its velocity.
This brings us to our last option: Increasing zero distance means adjusting your sights so your bullet strikes high at 100 yards, not dead on. Zero 2 inches high at 100 and your bullet might strike dead-on at 200 to 250 yards. Zero 3 inches high at 100 yards and it might hit dead-on at 280 or even 300 yards. This depends on initial muzzle velocity and B.C.
That’s Too High!
This seems to be everyone’s initial reaction to hitting 3 inches high at 100 yards. And it’s not far wrong. But closer examination reveals the true potential. Let’s say you’re aiming at a deer, pronghorn, sheep, or goat. All (except some really tiny subspecies of whitetail) will span 14 to 18 inches from brisket to withers. Within this span sit the vital heart, lungs, and spine covering roughly 10 to 14 inches top to bottom and about that far front to back. Vital tissue. What the old timers called “the boiler room.” Hit any of it and you’ll soon be skinning.
Let’s be conservative and say we have an 8-inch circle of vital tissues. That’s our target. Now let’s aim our rifle (zeroed 3 inches high at 100 yards) and engage this animal with a center chest hold. Four inches of our vital target will be above this aim point, four inches below. At 50 yards our bullet will still be rising, so will likely strike 1.5 inches below our aiming point. Score! At 100 yards our slug should hit 3 inches high, still within the vital tissues. At 150 yards we’re reaching our maximum ordinate, the high point of our trajectory with the bullet 4 inches above our aiming point. Wow! Four inches high! Yet, that still catches the upper edge of our 8-inch vital zone, upper lungs or spine. At 200 yards the projectile will have fallen, now landing about 3 inches high. At 250 yards it’ll be only about an inch high, and at 300 yards it might be 3 or 4 inches below point-of-aim.
Admittedly this isn’t gnat’s eyelash precision shooting, but we’re in the field hunting. We might have to shoot off-hand, kneeling, sitting, leaning over a branch or boulder, breathing hard, shaking from buck fever. Not many of us are going to be shooting 1/4 MOA anyway. And we might have to shoot quickly. A hit in the upper lungs is still a hit in the lungs. It’s all vital tissue within our 8-inch circle. So hitting 4 inches high isn’t a deal breaker. Hitting 8 inches low would be, and that’s more likely to happen with a 100-yard zero.
Trouble in Paradise
The above explanation makes our 3-inch high at 100 yards sight-in sound perfect, but we haven’t considered the complicating factors yet.
First, there is our rifle’s inherent accuracy window. If we have an MOA rifle, meaning it consistently puts all its shots into a 1.047″ circle at 100 yards, any shot we take has the potential for being 1/2 MOA off our aiming point. A half-inch at 100 yards is no big deal, but MOA is an angular measurement, so at 200 yards a half MOA would equal an inch, at 300 yards 1.5 inches, at 150 yards 3/4 of an inch. This is still not the kiss of disaster because by selecting an 8-inch vital circle, we’ve built in a bit of leeway. In truth the vital tissues probably cover more like 10 or even 12 inches. Nevertheless, our rifle’s consistency must be considered.
The next fly in the ointment is OUR consistency. Can we always aim and shoot precisely enough to keep our shots within that vital zone? From bench and sandbags, probably. From a prone bipod position, ditto. But sitting, kneeling or leaning over a pack? And with buck fever? We’ve all seen or heard about the guy who missed a buck standing broadside at 80 yards. Chances are we are that guy! How can this happen? Buck fever. Just as a pro basketball player at the free throw line puts up a brick with 1 second on the game clock, we miss a deer by two feet. But we’re not talking feet here. We’re talking inches, and from many field positions it isn’t unusual to open our groups to twice what they’d be from the bench. Put a 300-yard shot off by just one MOA and that bullet sails an additional 1.5 inches from target center. Add that to the possible 1.5 inches the rifle itself varies shot to shot, and you could be off 3 inches total. If your bullet is already dropping 3 inches at this range, it will now be falling 6 inches.
Last but not least, what happens if you don’t correctly see the deer’s center chest? If his brisket is camouflaged by grasses or brush, you may see only 2/3rds of the full chest. Split that in half and you’re already aiming 3 or 4 inches higher than dead center. Add in both of the above complicating factors and you’re shooting high. Been there, done that.
Moderation in All Things
Obviously these complicating factors should not be ignored. Unless you are shooting a sub-MOA rifle, calm and cool under pressure, and from a solid rest, a 3-inch high zero at 100 yards might not be best for you. No big deal. Just back down to 2.5 inches high or even 2 inches high. You’ll still extend your reach without compromising your mid-range shots to any degree worth worrying about — unless you truly are shooting gnats.
The Time and Place for 100-Yard Zero
There actually is a good place for a 100-yard zero. It’s where terrain and habitat limit shooting distances to no farther than 200 yards. For many stand hunters and even still-hunters in wooded country, this is reality. I’ve met hunters who’ve never taken a shot at a deer more than 100 yards away — or had the opportunity. And more were at 50 yards than 100. In such cases, a 100-yard zero is perfect. Trajectory curve of bullets from most bottleneck cartridges in the .243 Win. to .30/06 class won’t rise or fall more than 1.5 inches at any distance to 150 yards or so. Slower, flat-nosed bullets from slower rounds like .30/30, .32 Win., .35 Rem., .45/70 and such will be a bit more looping, but not enough to worry about.
How About a 300-Yard Zero?
Should anyone ever choose a 300-yard zero? For hunting? Maybe. A few hyper-velocity magnums like the 26 Nosler, 6.5-300 WBY, 7mm RUM and others with high B.C. bullets shoot flat enough that a 3-inch high zero at 100 yards translates into dead-on at 300 yards. Such bullets don’t drop 3 inches from point-of-aim until about 350 yards.
Another option for a 300-yard zero is a large target animal. A big bull elk’s chest is about 24 inches top to bottom with a good 16 inches of that vital tissue. Aim dead center and you have 8 inches of vertical target to work with. You could zero nearly 6 inches high at 100 before your mid-range trajectory would reach 8 inches high at around 175 yards. It wouldn’t drop 8 inches below POA until nearly 425 yards.
If those numbers sound crazy, imagine what you’d come up with using the target diameter of an Alaskan bull moose! Chest depth is nearly 3 feet! But I don’t recommend such crazy zeroing schemes because they mess you up when you get back to normal game. Ideally you should stick to a common target diameter that accommodates your smallest or typical quarry and become deadly with that. Then elk and moose will be a slam dunk. (Never mind the moose I once missed. Buck fever that time. Bad, bad case of buck fever.)
Do The Math and Test Firing
Regardless what zero range you choose, discover your trajectory at various distances by consulting and carefully studying trajectory tables as calculated by various on-line ballistic programs. Just do a Google search for Ballistic Calculators. In addition to or in leu of, you should test this on targets. Once you’ve set your zero, shoot paper targets at 50 yards out to 300 yards or so from a steady rest, always aiming for the bullseye center so you can measure how high and low your bullets strike. This, more than anything, will build your confidence. Any bullet hole within 4 or 5 inches of your aiming point represents a vital zone hit on a broadside deer.