HOW TO ZERO IRON SIGHTS AND OPTICS
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Today, we will cover the basics of zeroing your rifle, both iron sights and your optic. TOOLS FOR ZEROING Before we get too far into this, let's talk about the tools of the zeroing trade. You can usually get by with the tip of a bullet or coin if need be, but there are always better tools that will make the job much easier. A2 Front Sight Tool - The A2 front sight tool makes moving a front sight post up or down MUCH easier than the "bullet tip" method. In my opinion, this is a must-have for any range bag. Scope Multitool - This is great for all-around optic and iron sight set up. You can tighten up the screws holding your optics to the rail or make adjustments to the turrets to windage screws. Leatherman MUT - This is always a great all-around tool for your range bag. Screwdriver, pliers, knife blade, what else could you want? WHAT IS ZERO? Your zero is the distance at which the bullet will hit your target at the spot where your dot or irons are pointing. Bullets aren't like lasers, and they don't travel in a perfectly straight line. Rather gravity takes effect the second it leaves the barrel. With that said, bullets have an arc pattern they follow. At a straight line, the bullet arcs downward the moment it leaves your barrel. If you want the bullet to travel further, you must increase the arc upwards until the bullet hits where you want at its intended distance. This is a very simplistic view of how a bullet travels. There's a lot that goes into ballistics, but that's for a much later date. Let's also quickly touch on Height Over Bore. When zeroing your rifle, remember that you aren't looking directly through your barrel; you are looking over the top of it at whatever height your optic is (see image below). This comes into play a lot more when you are closer to a target than what your optic is zeroed at, as what you are looking at is a point higher up on the target than what the barrel is pointing at. If you are shooting close in but zeroed further out, you'll need to aim a tiny bit higher to hit the same point of impact. We'll touch more on this below. ZERO DISTANCES Now that you understand the concept of bullet arc and height over bore let's talk about zeroing distance. Remember, all things that go up must come back down thanks to gravity. At a flat range, you will be pointing your barrel ever so slightly upwards to compensate for gravity and hit your target at a specific distance. That means that the arc the bullet takes typically causes it to rise into the target, hit its apex at some further distance, then start falling again until it ends up in the dirt. If you think through this, that means you have two points at which the bullet is at the same height, once on the rise and again on the fall. So when you hear about 50-200 or 30-300 zeros, itís typically in yards in the US, and itís because the trajectory of the bullet at those particular zeros gives you a hit at 50 yards, then again at the same point on a target at 200 yards as it falls. The first thing to consider when picking a zero is the engagement distances you anticipate. For all of my 5.56 rifles, I choose a 50-200 as I don't shoot much past 200 yds when I'm located, plus the impact shift up or down depending on distance is minor until after 200. Now that may change for you, your caliber, your rifle, your distance. If you live on 10 acres of clear land and want to get the zombies at the very edge of your property, maybe a 30-300 would be better. That's up to you. Let's shift your brain a little further here. You should always be aiming for the same point, i.e., center mass, of your target. If it's 10 yards, aim center mass. If it's 200 yards, aim center mass. That means that the hole you leave in your target will rise or lower depending on the distance. Remember, your point of aim is constant, but the target distance will change where the impact is in the bullet's arc of travel, higher or lower. I like a 50-200 zero because the impact points for all distances out to 200 yds will be within a couple of inches, so you don't need to think a whole lot. The dot goes on target, and you squeeze the trigger. At 50 yds, it'll be right on, and at 200 yds, it'll be right on. Anywhere in between those distances will be a max of a couple of inches higher. At 250 yds, you'll be just below the sternum, and at 300 yds, you'll be at the navel. At 350 yds, you'll be at the groin. Anything beyond that, and I prefer a full-power rifle cartridge. There are plenty of other zeros you can explore which have benefits of their own. I'm getting old and stuck in my ways and prefer a 50-200 for my rifles. A quick internet search will bring up pages and pages of discussions on which zero is the best and why. Always remember that opinions are like butts, we all got 'em, and they all stink. ZEROING IRONS Now to the point you've all been waiting for, let's zero your irons. If you have a red dot, look for the next section. Iron sights come in all different forms and functions. For this discussion, we'll look at the most common flip-up iron sights on the market, the Magpul MBUS sights. Make sure that your irons are as far forward and back as possible on your rail (see image below). The longer the sight radius, the better. Don't forget to flip them up. Your front sight dictates the elevation of your round, and the rear sight changes the windage. If you didn't grab a handy front sight tool from the section at the beginning, grab a cartridge, we'll need to depress the lock on the top of the front sight post to turn it (see image below). Place your target at your desired zero distance. For me, it's 50 yards. Aim and take three shots. Take your time and be precise. Note where your bullets impacted, and be prepared to move your sights to correct. Raising the front post lowers the point of impact. Lowering the front post raises the point of impact. If you remember nothing else, remember that. The relationship of post height to bullet impact is inverse. Moving your rear sight left moves the point of impact left and moving it right moves the impact right (see images below). Make your adjustments in small increments and fire three more rounds. Repeat the above until you are consistently hitting your zero at your desired range. Now stagger some targets at different distances, shoot for the same point of aim, and notice where the impact lands. ZEROING OPTICS When talking about red dot zeroing, we will look at one of the most common and affordable dots on the market, the SIG Sauer Romeo 5. When it comes to the Romeo 5, you don't need any tools because they are built into the top of the adjustment caps. Place your target at your desired distance, aim, and take three shots to see where you are. To move the point of impact up, rotate the upper turret counter-clockwise. To move the point of impact down, rotate the upper turret clockwise. To move the point of impact right, rotate the right turret counter-clockwise. To move the point of impact left, rotate the right turret clockwise. Remember to make minor adjustments and take a couple of shots as you go. When you are done, replace your turret caps and fire a couple more rounds to make sure you are satisfied with the zero. OPTIC CO-WITNESS The last thing to touch on is optic and iron co-witness. Irons are typically at a fixed height across the board, so the height of your optic mount will determine your co-witness. An absolute co-witness is where the irons line up with the middle of your red dot. Absolute co-witness brings your head down and gives you a solid cheek weld. I usually suggest a low cheek weld and absolute co-witness if you are shooting a longer-range rifle. Lower 1/3 co-witness places your irons in the lower 1/3 of your optic, which means your head is up a little higher. A head-up position is better for more active shooting, clearing rooms of the zombie plague, or running around larping in your undies pretending you are a tier 1 guy. My wife loves it when I do that. CONCLUSION Zeroing your optics or irons isnít tough but absolutely a must and should be done well, not just good enough. Set yourself up for success by making sure your rifle hits point of aim even if you arenít able to yet. This is one of those basic skills that every shooter should perfect and be comfortable doing when needed. Take your time and enjoy the range trip.