What does zero mean?
Understanding zero is important shooting accurately. When we first start shooting AR15s, understanding the concept of zero and how to zero your rifle gets a bit confusing. Zero refers to setting your sights or optics so that your point of aim is the same as your point of impact at a certain distance to your target. Your zero is for that distance only. If you shoot at any other distance, the bullet will impact lower or higher depending on where you are in relation to your target. In other words, if you zero at 100 yards, you will only be dead on at 100 yards. Every other distance will require some type of adjustment in your point of aim.
Zeroing becomes confusing because it involves your line of sight and you expect your rifle to shoot the same way. Your line of sight is in a straight line to the target but the bullet’s travel is not. Bullets travel in an arc, yielding to the forces of gravity as soon as it leaves the barrel. Think in terms of throwing a ball. The shorter the distance the straighter the line to your target. The farther the distance, the higher up you must throw the ball to get to your target. The way you point your barrel does the same thing. If the bullet never stopped till it hit the ground, the bullet would cross your line of sight twice as it rises in the arc and then comes back down. Therefore you’ll hear the terms near and far zero when dealing with this issue. You might hear it expressed as something like 50/200. The 50 is your zero distance (near zero) and the 200 is where the bullet comes back down to your line of sight the second time (far zero).
Sight Height Above Barrel
Another factor that plays into your zero, is the height of your sights (or optics) above the barrel. For example, most ARs have an approximate 2.5-inch difference between your line of sight and where the bullet comes out from the muzzle. That means that when you are looking at your target, the muzzle is lower than your line of sight. If you shot at a target right in front of you, you would notice that the bullet struck 2.5 inches below where you were aiming at. This height difference plays a part in you zero calculations.
Many people get confused because there so many distances to zero your rifle. There are no standards to follow unless you are in the military. And even then, different branches of the military zero at different distances. Adding to this confusion are well-intentioned friends and the hundreds of internet articles that have plenty of advice for you except it might all be wrong for your given situation.
My Zero Distance and Why
You 1st need to decide what you are going to use your rifle for. For example, on my Live Free Armory 5.56 carbine, I have a scope and offset fixed sights as backup sights. I have chosen a 50 yard zero for this rifle for two reasons.
First, it’s what I’m used to from my law enforcement days. Second, it puts me right on at 200 yards because of the way the bullet travels. I can also shoot out to 300 yards by making a slight adjustment in where I aim. It’s all I need for the type of shooting I do. Here is one of my favorite articles on a 50 yard zero in case you want to find out more about this method.
Your Needs Might Be Different Than Mine
You may have a different need than I do. If you are looking for home defense, then your zero will probably be a shorter distance. Maybe you want a general purpose AR15 and the 50/200 zero, like the one I use, is for you. Or, if you’re a hunter, you might use maximum point-blank range (MPBR). MPBR is the maximum distance over which a shooter can hold his sights on the center of the target and hit it. If you set your MPBR for a six-inch circle, you could hit your target 3 inches high or 3 inches low and still score a hit. With the ammunition I use, I can keep it in six inches up to 275 yards and still hit what I am aiming at. In theory anyway, as six inches is still a small circle especially at 275 yards! You figure out your MPBR using a shooting calculator and plugging in the information it asks you. I happen to like this one from ShooterCalculator.com.
So, there you go. Zero is nothing more than setting your sights so that your point of aim is the same as your point of impact. You get to decide what it will be.
If you’d like more information or have any questions, feel free to email me at Murgado.firstname.lastname@example.org. Please remember that Live Free Armory is here to help you whether you choose to buy from us or not. We believe that obtaining the right information should always be your first step.