In a little over a year, I’ve sold nine guns that, after buying them, I decided weren’t for me. Did I take a haircut on my firearms flips? Sure. But on the plus side, each one was a learning experience.
I’ve also spent a good amount of time getting training. Over the past year, I’ve amassed over 120 hours with more to come. The latest example of this came about at the two day SIG Sauer Academy Defensive Rifle class. We learned plenty in this class (more on that in a future post), but one of the things that we spent some time on is understanding the proper zero distance for our optics.
Prior to this class, most of my rifle shooting was done on a 300 yard range and I zeroed my optics and iron sights at 100 yards. Everything I’d read and the ballistic programs I got for my iPhone all seemed to default to 100 yards, so that is what I assumed was the “right” distance to use.
In the class, though, we got a different perspective. The instructor emphasized that every decision you make — from the equipment you carry to the distance you zero your rifles — should be designed to fit whatever your current mission is. If your mission is to be the designated marksman or sniper, then perhaps a 100 yard (or longer) zero distance might be appropriate.
But for the standard AR-15 patrol rifle sporting an unmagnified red dot optic, the suggestion was to use 50 yards. The argument to support this suggestion is simple: the typical infantryman, police officer or responsible citizen protecting his or her property just isn’t as likely to find themselves engaging targets beyond the 0-275 yard “comfort” zone range of the AR-15.
Does that mean that you’ll never need to shoot any further than 275 yards? Of course not, but it is very likely that if you are part of a military or police unit, chances are there will be at least one other guy on the team sporting a gun better suited to long range engagement, and the responsible citizen isn’t likely to find themselves having to engage enemies at extreme distances.
The typical AR-15 user in urban combat conditions will most likely never need to go much past 200 yards, let alone 275 yards. Since it’s likely that the “mission” of AR-equipped shooters will be short to medium range engagement, it makes sense to zero your rifle at a distance that will give you the greatest latitude. The chart below maps the ballistics of the standard 55 grain bullet fired out of a 16″ barreled M4 style carbine.
Pay attention to the zone on the chart between the two yellow horizontal lines. That represents 4 inches above and below the zero line, making a total vertical distance of 8 inches. You’ll see why this matters in a moment. Looking at the three ballistic traces, you see that the 50 yard zero, designated by the red line, remains within this 8 inch zone out to just shy of 275 yards. The 100 yard zero is nearly as good, but that round falls outside the 8-inch zone shortly after passing 225 yards.
Why do we care? Well, consider that if the “mission” is to clear a room or defend your property, you arentt likely to be particularly concerned where on the target your round hits, just as long as it’s center mass. If you envision a person with an 8-inch circle on his chest centered roughly near the bottom of the sternum, you’ll quickly find that there are few places you can get hit within that 8″ circle where something major won’t get pulverized by ordnance passing through it.
And that’s the argument for the 50-yard zero for personal defense applications. Will this work for you in competitions? I guess that depends on the competition. Obviously, if you’re in a long range target shooting competition where the number of X’s determines who wins, this method wouldn’t be ideal.
Things might be different in a 3-gun competition where the objective is to hit a steel plate and where you hit the plate you isn’t so important. Hunting, of course, would be still another story. In many hunting situations, you have a relatively small kill zone and may very well want to hit a target further out than 275 yards. Then again you’d probably be using magnified optics with features that allow you to adjust your aim based on the distance from the target.
Looking at that chart again, consider something else; let’s say that your target is presumed to be wearing body armor. This is much more likely to be the case for a military or police user – if a responsible citizen is in the position where they’ll be engaging armored targets, that’s a different kettle of fish.
Once again, let’s draw a circle, but in this case place the center of the circle on the target’s nose. Now we’re probably talking about a 4 inch diameter, give or take. In this case, even at shorter distances, the situation would probably call for a 100 yard zero.
Out to about 175 yards, the 100 yard zero deviates less from the point of aim than the 50 yard zero does. But once you pass 175 yards, the 50 remains good out to just shy of 250 yards. So, again, you have to consider the mission. A LEO isn’t likely to be engaging targets beyond 175 yards, so the closer the bullet travel holds to the point of aim, the better. Then again, a soldier might well want the extra 75 yards afforded by the 50 yard zero if they’re likely to engage targets in the open at distance.
Is the 50-yard zero ideal for everyone in every case? No, and that’s the point. You need to choose the set-up that fits the mission. For me, I have other rifles with magnified optics and larger calibers that are more suited for long distance shooting, so I can safely relegate my trusty Sig 516 to the role of a short to medium range defensive weapon. As in all things, YMMV.