When you miss, it's always good to know why. One of the most common reasons for missing a shot, particularly a longer shot, is not figuring the correct range to the target. In close, an error in range estimation may not make enough difference to matter. But farther away, that same amount of error can often mean a miss. The reason is that even though we all know that a bullet drops below the center of our crosshairs when we shoot beyond the distance for which we have zeroed, many of us don't fully understand how quickly the rate of that drop increases, the farther out we reach. Let me explain.
Let's say you're hunting with a 150-grain softnose .308 Winchester load, which is one of the most popular whitetail cartridges in America. It leaves the muzzle at about 2,820 feet per second, according to the manufacturer's ballistic chart, and you have zeroed your gun at 100 yards, which is the most commonly used sight-in distance among all deer hunters. You've studied that chart, and you know that with a 100-yard zero your bullet will hit about 1.2 inches low at 150 yards, 3.75 inches low at 200 yards, and a whopping 14.25 inches low at 300 yards - should you ever dare to shoot that far. You're prepared to deal with that, because you have a scope with a trajectory-compensating reticle, and you've checked to make sure where the bullets actually hit by firing at known-distance targets on a shooting range.
But when you get to the field and encounter an animal that's not standing at exactly 150, 200, or 300 yards, what happens if you don't correctly determine how far away he really is? Well, if you use that .308 to shoot at a deer you think is 100 yards away and he's actually at 150 yards away, it probably won't make enough difference to matter, because the bullet only drops an inch and a quarter crossing that additional 50 yards and you'll still be well within the kill radius if you've aimed for the center of his heart/lung zone.
But what if you think he's 200 yards away and he's actually 250 yards away? Different story. Your bullet is going to drop an additional 4.3 inches below the 200-yard impact point traveling across that additional 50 yards. So even if you put your reticle's 200-yard drop marker right on his heart, you're going to hit more than four inches low. You're going to miss his heart, and probably shoot under him entirely, even if you're steady as a rock when you press the trigger.
And, if you range a deer to be at 250 yards (which is a shot at a trophy buck most of us would take in a heartbeat with a .308), and he's actually at 300 yards, you won't even touch a hair, even if you've got your aim solidly placed for the 250-yard distance, because traveling that additional 50 yards from 250 to 300, the bullet is going to drop yet another six and a quarter inches.
The same applies when we are hunting with handguns, slug guns, muzzleloaders (or even bows), as well. A lot of hunters think that trajectory issues and bullet drop issues are really only important for long-range rifle hunting. Not so. In fact, the problems caused by mistaking the range to your target are often even greater with such "shorter-range" hunting tools than with a high-power centerfire gun. Handguns, slug guns, and muzzleloaders are not as "flat-shooting" as centerfire rifles; their bullets drop quicker and at a faster rate.
Consider a modern full-rifled 12-gauge slug gun firing a high-tech 260-grain sabot slug that leaves the muzzle at about 1,900 fps velocity. If zeroed at 50 yards (still a popular sight-in distance among slug hunters), that slug only drops 1.7 inches by the time it gets to 100 yards. Again, not enough to make a telling difference. But if you think your buck is 100 yards away and he's actually 150 yards away, your slug is going to hit more than five inches below your 100-yard aiming point.
My own personal favorite new-technology 12-gauge sabot "slug-rifle" will shoot 150-yard groups that are right at two inches with its favorite load, and it will hold a four-inch group at 200 yards. I have no aversion whatsoever to going for a trophy shot at either of those distances with that gun if the opportunity presents itself. But what if I guess the range at 150 and it's closer to 200? There is nearly a full foot of drop for that slug across those 50 yards. It doesn't matter how accurate the gun is, or how well I aim for the distance I think the animal is standing. If I don't have the range correct, I might as well be throwing rocks. And as it gets farther away, the drop becomes increasingly worse, at an increasing rate.
How easy is it to make incorrect range estimates in the field? Really easy, even between 100 and 150 yards, even for the most experienced hunter, depending on terrain, vegetation cover and the size of the animal as it appears through his scope. Out at 200-250 yards, or 250-300 yards, it's a rare hunter who can guess distance with enough accuracy to overcome the problem of their bullet's rapidly decaying trajectories, particularly when hunting in unfamiliar country. I can't, and I'm better at it than most. How dare I say that? Because I've practiced, practiced, practiced, everywhere I hunt anything across the country, making guesses on how far rocks and trees (and animals) are away, and then verifying with a laser rangefinder.
When hunting with others, we do it as a game, each guessing, then verifying. I win more than I lose, but not so much these days as before, now that more and more hunters are playing this game because they're becoming more aware of just how fast their bullets drop the farther out they get.
The laser rangefinder is the critical tool in all this. Get one if you don't have one, no matter what firearm or archery device you hunt with, and use it - all the time. When hunting on the move, have it attached to your body, clothing, or gear with some type of auto-returning retention device (there are many) so you can instantly throw it up to your eye and get a read, then release it to take your shot. When hunting from a stand or a blind, use the rangefinder to mentally mark known distances to landmarks (bushes, trees, fenceposts, rock outcropping, whatever) all around you, so when something steps out, you'll already have a close-enough estimate in your mind of how far away he is.
Bottom line? Know your gun's trajectory. Shoot it at known-distance targets to make sure you know how your scope indexes at different key distances. And use a laser rangefinder in the field — every single time you hunt.