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Revised Notes On Zeroing The Defensive Carbine

A few years ago, I wrote some advice for getting bullets launched from your AR-15 type on paper.

I’d like to amend my post and instead recommend you read and pay close attention to what Jack Leuba and Kyle Defoor have written on the 100 yard zero. I applied this to my own rifles and had excellent results both with the irons on both rifles, and my Aimpoint.

The big advantage of the 100yd zero over the 55/200 is that the bullet does not rise above the line of sight and for precise hits the shooter only has to aim higher at 200ish yards, instead of having to remember where he’s going to hit high and where he’s going to hit low. For the vast majority of potential civilian uses, no adjustment at all is required. In fact, I ran my target out to the 200 yard line and was only hitting a few inches low.

Why buy one when you can have two at twice the price?

Why buy one when you can have two at twice the price?

Some post-range trip notes:

I regard the iron sights as my primary sighting device. I worked first on getting a good, solid zero with my irons before I even screwed my optic on. Unlike optics, iron sights do not break, fall off, fog up, run out of batteries, or get covered in mud, snow, ice, blood, dirt or water. Modern Aimpoints have amazing battery life and are surprisingly durable, but they still break. If your rifle doesn’t have iron sights, you don’t have sights on your rifle.

Therefore, I have come to prefer non-folding sights. I suppose a sturdy folding rear is an option if you have a 1-4x optic that doesn’t allow for a fixed rear, but I would recommend a steel unit like the Troy over the Magpul rear, which I am not impressed with. I particularly prefer a fixed front sight base to a folding or screwed to a rail front. At first I was concerned that the clutter of the sights would make using the Aimpoint confusing or difficult, but I’ve found when I’m focused on that dot, the details blend into the background.

For fixed rears, I have both a Daniel Defense 1.5 and a Troy fixed rear. Both are excellent, easily adjustable and pretty much interchangeable. Pick whichever looks better to you.

Daniel Defense 1.5 Fixed Rear Sight

Daniel Defense 1.5 Fixed Rear Sight

Troy Industries Fixed Rear Sight

Troy Industries Fixed Rear Sight

For my iron sights, I set elevation such that I was hitting 1.5″ high at 100 yards to compensate for the natural urge to put the front post under the target. After I was satisfied, I then shot a few groups at 100 from different positions, and checked where I was hitting at 25 and 50 yards. Note that I did not perform any adjustments here, this was only to see how things looked under various conditions and ranges. Then I repeated the whole procedure with the Aimpoint screwed on.

Verify your zero at a variety of distances, from a variety of positions.  And get off the damn bench.

Verify your zero at a variety of distances, from a variety of positions. And get off the damn bench.

I had a moment of derp when I put the dot on target at 100 yards and the optical blooming of the dot obscured not only the bullseye but totally covered up the target frame. After contemplating my advanced age and the cost of getting prescription glasses, I remembered the Aimpoint brightness adjusts down as well as up.

I also double checked my 100 yard zero with the Aimpoint after removing and reinstalling it, and I was hitting in the same spot.

All this cost about 60 rounds per rifle of precious brass-case ammunition. I mostly used my miscellaneous 55gr XM193 leftovers from various manufactures, but sparingly used 30 rounds of my Federal / Lake City XM193 stockpile for final verification. Then I busted out the cheap steel cased fodder and blasted through about 120 rounds per rifle. The good news is that during assembly, everything pinned, screwed and snapped together with much less aggravation than my first AR. The great news is that both rifles functioned perfectly and dumped their cases in neat little smoking piles. Accuracy was about what you’d expect from a 16″ chrome lined carbine shooting military ammunition, about 4″ at 100 yards. This opened up to 6-8″ shooting Russian steel cased ammo, but interestingly, the 62gr ammunition grouped to about the same point of impact as the 55gr.

No, I don't know how to remove brass marks from the upper.

No, I don’t know how to remove brass marks from the upper.

Oh yeah, I totally forgot to lube up the rifles before hitting the road, so I stopped at a gas station on the way to the range and bought a quart of 30W motor oil for $4. This worked fine and should be a lifetime supply. I did, however, revert to my usual combo of light oil in the lower and lithium wheel bearing grease on the bolt after cleaning.

I was relived that most of my component choices not only worked, but worked well together. The only thing I’m going to replace is the Cavalry Arms A1 buttstock. It’s too short for the Blackhawk buttstock magazine pouch and doesn’t allow the charging handle to be fully retracted. The Magpul furniture is superb. The handguards fit well and are comfortably shielded, even after firing two magazines fast enough that the assembly lube was smoking. The MOE fixed stock is the perfect length for me, for all field positions. The MOE grip is pleasantly meaty without feeling bulky, and has a subtle rubbery texture instead of the hard GI plastics. The days of stuffing a foam earplug in the A2′s pistol grip gap are over, get a real grip. They’re only $20!

I did not notice any difference in perceived noise or recoil (it’s a 5.56! It doesn’t recoil!) between these 16″ carbines and my 20″ A1. The heavier barrel profiles and the flashlights made them feel less lively, but this is a subjective judgment and I didn’t bring my A1 along to shoot back to back.

I think the ALG ACT trigger group is a tremendous value. For only $60, you get a consistent trigger pull with all the durability of the stock GI trigger group. It is a single short rolling stage of about 6 pounds. It’s heavy enough to be safe, light enough to allow for precise shots, and the break is enough of a surprise that your concentration can be on your front sight. An unexpected benefit is the smoothness with which the safety lever glides from position to position. It locks positively in either, but the motion between is like sliding an ice cube across the counter. I do have one issue with one rifle, the safety is difficult to engage with the bolt locked back. I’m not sure if this is an issue or not, I have an email out to the ALG people.

The “primary” carbine weighs in at 11.46 pounds ready to roll, with 2 loaded 30 round Pmags onboard. Heavy, but not cumbersome. Backup carbine tips the scales at 8.7 pounds with a loaded Pmag, flashlight and sling. I will be adding a MOE buttstock, Blackhawk magazine pouch and Aimpoint as funds allow, but it is quite useable for now.

Roll out, smoke fools.

Roll out, smoke fools.

Done... for now.

Done… for now.

For the future, the only thing I want to do with Primary is shoot it some more, whenever ammo becomes reasonably available again. I also have a strange lust for the newly announced Troy Battle Rail Delta Midlength, which combines my love of fixed front sight towers with the slim and trim free-float tube trend. It wouldn’t do anything for me other than make the rifle look about 20% more ninja, but I still want it.

The smarter thing would have been to spend about the same amount of money and get two Colt 6920s from Wal-Mart, but I thoroughly enjoyed piecing together my own rifles and feel that I’ve learned more about the platform in the process. I can’t recommend you do the same and can’t promise you the same results, but the state of the modern AR industry is truly amazing. We have never had such a richness in options, support and quality from which to choose.

{ 1 } Comments

  1. TomcatTCH | March 7, 2013 at 12:30 pm | Permalink

    The Troy battle rail will probably reduce your weight just a bit. The MOE handguards are actually fairly heavy, and if you include the delta ring and handguard cap, I’d bet if the the troy rail isn’t lighter, it’s because it’s longer.

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  1. [...] my iron sights and my 12-o’clock-mounted Inforce WML. After doing some reading (including this post at PDB), I’m going to likely dump my current 25-meter zero for a 100-meter zero to minimize [...]