Revisiting the Carbine Zero…

In the interest of full disclosure, I’ve been sitting on this post since I first penned it in October of 2018. My opinion has evolved somewhat over that time, but hasn’t fundamentally changed. So, I’m going to go ahead and share it here. In discussing the best zero for a carbine (AR-15, etc.), I think it is much like gear, an individual choice dependent upon unique circumstances. So take this for it’s worth, just the experience of some random dude on the internet. I will say that my opinion has been heavily influenced by training with Paul Howe, Kyle Defoor, and Bill Rapier, and reading the writings of Jeff Cooper, John Mosby (The Mountain Guerilla), Grant Cunningham, and Clint Smith.

For a long time now, I have zeroed my carbines and rifles at 100 yards across the board. I first learned to do this during my initial carbine class nearly fifteen years ago with Paul Howe (Combat Shooting and Tactics). The 100 yard zero has been reinforced for me at virtually every training course since. Indeed, there are some really good reasons to adopt this zeroing scheme.

  • Most everyone can find a 100 yard range to shoot at, but that is often the maximum distance available.
  • Most optics with bullet drop compensation reticles are designed to be zeroed at 100 yards.
  • Target identification and discrimination beyond 100 yards is difficult without magnified optics.
  • You will never have to aim low with a 100 yard zero. If anything, you will have to hold over, which is an easier concept for most people to grasp than holding low is.

For some more really good arguments for a 100 yard zero, check out this link and read Kyle Defoor’s thoughts on the subject.

Another very common zero that is widely suggested is the so called “50/200” zero. This refers to two points of intersection of the bullet’s trajectory with the line of sight. First, a near zero of 50 yards. Then, the bullet’s trajectory will rise above the line of sight and then again fall below the line of sight at roughly 220 yards. I hesitate to use the word “rise” since gravity is omnipresent. After the bullet leaves the muzzle, it is subject to gravity and is falling. What’s actually happening is that the bullet is propelled above the line of sight before gravity pulls it back down across the line of sight. When we adjust our sights, we are essentially adjusting how far above the line of sight we propel the bullet.

This is of course dependent on a number of factors such as velocity, bullet weight, and barrel length. With a 50/200 zero, you need to true the rifle out to 200 yards and beyond to see where the bullet is actually hitting at the various distances with your gun and ammunition. This zero scheme essentially represents a “point blank zero” for the carbine. In other words, from contact distance out to at least 200 yards, you should be able to hold center mass and hit the vital area of a target. Note that the maximum point blank range of your gun is directly dependent on the size of the vital zone, i.e. 4 inches. The larger your vital zone, the farther your maximum point blank range. Imagine shooting through a long cylinder. The distance that the bullet can travel without hitting either the top or the bottom of the cylinder is the maximum point blank range. The larger the diameter of the cylinder, the longer the maximum point blank range.

Finally, there are the military standards of 25/300 (meters for the Army) and 36/300 (yards for the USMC), similar to the concept I describe above. For any number of reasons, I don’t think these zeros are necessarily a good idea for the average civilian. The two primary problems with them are the need to confirm at the far distance and the need to hold low at closer ranges.

For a really good graphical representation of these different zeroes, check out this link at Arma Dynamics. I’ve never trained with these guys, but I like their printable targets.

With all that background explanation out of the way, I want to discuss the zeroing scheme that I’ve settled on.

A few years ago, while deciding which optic to mount onto my SBR, I mounted my Aimpoint Micro T1 on the gun and zeroed it with some of the ammo that I had received from Target Barn. Specifically, I used PMC X-Tac 77 grain OTM, since I wasn’t really pleased with the performance of Wolf Gold out of the short barrel.

Before I zeroed my SBR, however, I zeroed my hunting rifle with the ammunition that I intended to hunt with that year. I did this at 100 yards, of course. Unfortunately, it was a dark and rainy day at the range, but that was the time I had available and the firing line was covered. With my Leupold VX-3i scope, I was able to see the target just fine at distance, and got my zero dialed in relatively quickly.

I then pulled out my SBR and began the zeroing process. Much to my dismay, I couldn’t clearly see the target I had put up at 100 yards through my Aimpoint Micro. Whether this was due to my poor eyesight or the weather conditions at the time is largely irrelevant. The fact remains, there was no way I was going to be able to zero my gun at that distance if I couldn’t visually resolve what I was aiming at! I decided to compromise and moved my target stand to 50 yards.

With the distance halved, I was able to achieve a decent 50 yard zero despite the conditions and decided to quickly see if the 50/200 theory was at all valid for my SBR and ammo. Indeed, on an approximately 18″ square steel plate hanging at 200 yards, I got a first round hit holding the 4 MOA dot on the center of the plate. While I didn’t establish the bullet’s exact trajectory at 100 or 200 yards, I was nonetheless gratified to hear the steel ring.

On my drive home, I got to thinking about sights and optics and my own visual acuity. I floated the idea by Robert of zeroing non-magnified optics at 50, and magnified optics at 100. Great minds think alike, and Robert responded that he had been considering the same. Both of us base this on the fact that neither of us is blessed with naturally good eyesight, and zeroing a gun at 100 with no magnification can be difficult for us. Ultimately, without magnification (and with modifiers), I’ve concluded that I can probably achieve a better zero at 50 than I can at 100.

Returning to lessons learned from Paul Howe, he has posted a video explanation of how he zeroes his rifles. Having read his writing on the subject, as I understand it, he uses a 100 yard zero with a built in offset. Although he is obviously not a fan of it, this is in effect very close to a 50/200 zero, represents a point blank zero, and allows him adequate hits out to 300 yards. The difference, and the point I believe he is trying to make, is that he actually verifies where the zero hits from 7 yards all the way out to 300 yards. Howe asserts that most people who use the 50/200 zero don’t actually know where their gun hits anywhere beyond 50. This is probably accurate and is symptomatic of a lot of mediocre training and standards that are in use today.

Now, I only have access to a 200 yard range, and my eyesight is what it is. The concept that I’ve been playing around with is to get the absolute tightest and best zero I can at 50 yards. Next, I verify windage and check my hits at 100 yards. Finally, I fire a group at 200 yards, just to see. My groups at 100 and 200 yards aren’t always all that impressive, but it gives me a true sense of my capabilities and where my gun hits. There are some definite limitations… the legacy Aimpoints I currently own both have 4 MOA dots. That means the the dot covers 4 inches of the target at 100 yards and 8 inches of the target at 200 yards! As well, I really do have difficulty visually resolving the dot against the target at much past 100. Finally, I make no claims of being a crack rifle shot, at least not at distance.

This is a group on the pasty at 50 yards. Considering the dot covers two inches of target at this range, I’m okay with it.
About 1.5-2” high at 100 yards…
While not an impressive group, all hits on the silhouette at 200 yards.

For now, I plan to maintain a 100 yard zero on my guns that have magnified optics. Magnified optics may not help me shoot better, but I can see the target better! I still think that it is a superior zero for all the many reasons enumerated above. But try as I might, I struggle at 100 with iron sights and non-magnified optics, so I’m going to commit to a 50 yard zero with those sighting systems, with verification of my trajectory at longer ranges as best I can. If I ever get better glasses, or am able to improve my marksmanship, I may yet go back to the 100 yard zero across the board. But for now, I’m satisfied with a 50/200 zero.

What zero do our readers like, and why? Feel free to comment below!

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4 thoughts on “Revisiting the Carbine Zero…

  1. For semiautos, I’ve been doing what you suggest: 50 yard zeros for irons and non-magnified optics, and a 100 yard zero for my one rifle with an LPVO. My .308 bolt gun has a 300 yard zero and dope out to 600 yards; the scope on it allows me to see that far.

    Liked by 1 person

  2. On one hand, I don’t want to say Defoor and Howe are wrong, they’ve got more combat experience than I ever will. I am sure they are right at least in their context. OTOH, I’m not going OCONUS to shoot people – I shoot competition and classes, plus maybe the extremely rare home defense situation at suburban distances. For my purposes, a 100yd zero basically means holding over quite a lot at the ranges I typically shoot at, which isn’t a big win for me.

    Here’s my rule of thumb for rifles, which has mostly served me well:
    Irons/Red Dots: MPBR for the rifle and most frequently used ammo combo. I use Strelok Pro and a chrono to calculate this, and then I capture it in a spreadsheet. Like you, I think the closer you are, the tighter your zero is going to be, and this has certain benefits.
    Magnified Optics: Whatever it’s supposed to be zeroed for (which tends to be 50yds for modern BDC LPVOs, and 100yds for everything else).

    Liked by 1 person

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