36yd lpvo zero pros and cons

[vicious_cb]

What is the reticle for your LPVO?

I had my Steiner P4Xi zeroed at 200 yards for the simple fact that was what the reticle called for. Was the BDC exact out at range? No. But they were on enough out to 500 yards that they would still score first round hits on IPSC steel.

For my red dots I like the 50 yard zero. Whether it's a little high or a little low at 200 yards doesnt really matter. Not that I can even realistically hold the difference at 200 yards with a red dot. I use it as a combat zero that gets me good COM hits from 0-300 yards. If it starts getting out towards the outer edge of the envelope, I just favor high on the target.

Pretty much this, its all about the reticle. Just download Strelok and pick the zero that will make your preferred ammo match up the best with your BDC or whatever reticle you are running. As long as they end roughly matching the hash marks and you know what distances each mark corresponds to it doesnt matter which distance your zero is at.

[SteyrAUG]

The 36 yard zero was originally nothing more than a field expedient distance (near zero) for obtaining a 300 yard far zero when using the M16A2 with its 20” barrel firing M855.

Pop quiz.

What is the most commonly missed target on the US Army 300 meter pop-up range, when using a 300 meter zero?

a.) 50 meter target
b.) 150 meter target
c.) 300 meter target
d.) None of the above

AR-15 Zeros and Trajectories

The 100 yard zero with a .223/5.56mm AR-15 carbine is a unique trajectory in that the bullet just “kisses” the line of sight at 100 yards and rides along it for approximately 10 yards before dropping back down below the line of sight. (Technically, the bullet does travel above the line of sight, but by only 0.010”; a fraction of the diameter of the bullet itself.)

For all other zeroing schemes, there are going to be two points were the bullet crosses the line of sight; the near-zero and the far-zero. For the near-zero, the bullet will cross the line of sight while traveling upward from the muzzle toward the apogee or “maximum ordinate,” its highest point of travel. For the far-zero, the bullet will cross the line of sight while traveling downward from the maximum ordinate.

Now, when assigning a name to a particular zeroing scheme, it would be helpful if that name gave descriptive information about that particular zero; that is, the name should give us information about the trajectory and how it is unique and differs from other trajectories.

As a point of reference, the Santose Improved Battlesight Zero is often referred to as a 50/200 yard zero, however this is incorrect. It is actually a 50 yard/200 meter zeroing scheme; and this is only with a very few particular combinations of bullet weight, barrel length/muzzle velocity and height of sights above the bore. As an example, a 20” barreled AR-15 A2 firing 62 grain M855 will not match the 50 yard/200 meter IBZ. Neither will a 16" barreled RECCE firing 77 grain MK262, nor a 14.5” barreled M4 carbine firing the 70 grain 5.56mm Optimized "Brown Tip" load. The same concept applies when people refer to a 50/225 yard zero. Only a very few specific combinations of bullet weight, barrel length/muzzle velocity and height of sights above the bore will match that description.

What this is all leading up to is this; except for a very few specific combinations of bullet weight, barrel length/muzzle velocity and height of sights above the bore, a 50 yard zero is a different zero than a 200 yard zero. For a 200 yard zero, we know that this trajectory will produce a far-zero in which the bullet will cross the line of sight at 200 yards in its downward travel from the maximum ordinate. (It is physically impossible to produce a 200 yard near-zero with any of the commonly available loads and barrels lengths used in .223/5.56mm AR-15s.) Other than for a very few specific combinations of bullet weight, barrel length/muzzle velocity and height of sights above the bore, the near-zero of the 200 yard zero will not be at 50 yards.

Conversely, a 50 yard zero tells us that this trajectory will have a near-zero in which the bullet crosses the line of sight at a distance of 50 yards in its upward travel to the maximum ordinate. For those who think that a zeroing scheme must be named after its far-zero, it is physically impossible to produce a far-zero of 50 yards with any of the commonly used loads and barrel lengths in .223/5.56mm AR-15s. The 50 yard zero can only be the near-zero.

Here are a couple of illustrations to aid in understanding some of the concepts described above. Lets start with the 100 yard zero as a reference point. As described above, with a 100 yard zero, the bullet’s trajectory just “kisses” the line of sight at 100 yards. Now, let’s increase the elevation setting of the sights/scope. As this is done, the near-zero can only move closer and closer to the muzzle. Concomitantly, the far-zero moves farther and farther away from the muzzle.

For the next illustration, we’ll start with the 100 yard zero again, only this time let’s decrease the elevation setting of the sights/scope. As this is done, the bullet’s trajectory can only fall away from the line of sight. The bullet will never cross the line of sight again; no zero at all.

Other than for a very few specific combinations of bullet weight, barrel length/muzzle velocity and height of sights above the bore, the far-zero of the 50 yard zero will not be at 200 yards; and for all practical purposes it matters not one bit. Whether the bullet crosses the line of sight for the second time (far-zero) at 189 yards, 200 yards, 215 yards or 225 yards will not make the slightest bit of difference in the practical application of the AR-15 as a defensive weapon. In each case we will be holding the same POA (beyond CQB distances) and know that we will be hitting within approximately 2 inches above or below that POA out to 200 yards (or farther depending upon barrel length and load.) You should have an idea what your actual far-zero is when using a 50 yard zero and confirm such at distance when possible, but again it’s most likely not going to be a 200 yard far-zero and again it does not need to be.

Choose your zeroing scheme based on the pertinent facts; not nonsense about “shooting through a cone.” When shooting at human targets, in the grand scheme of things there isn’t going to be any practical difference between a point of impact that has a negative deviation from the point of aim, (e.g. the bullet strikes 1.5” below the point of aim) and a point of impact that has an equal positive deviation from the point of aim (e.g. the bullet strikes 1.5” above the point of aim.) In other words, the absolute value of the point of impact from the point of aim (how far the point of impact deviates from the point of aim, regardless of whether it is a positive or negative deviation) is what we need to be concerned about. Therefore, one of the main points to consider when choosing a battle-sight-zero is this: What zeroing scheme produces the smallest absolute values for the deviations of the points of impact from the point of aim, over the distance that we reasonably expect to engage a human target in our intended usage?

The chart below illustrates the above concept. The chart compares the absolute values of the deviations of the points of impact from the point of aim (0.0 inches on the graph being the point of aim/line of sight) for a 50-yard-zero and a 100-yard-zero, using Hornady 5.56 TAP T2 ammunition.

As you can see in the graph above, from the muzzle (0 yards) to approximately 62 yards, the 50-yard-zero has a slight advantage over the 100-yard-zero. Between the distances of 62 yards and 165 yards, the 100-yard-zero has the advantage. From the distance of 165 yards out to the 250 yards shown in the graph, the 50-yard-zero has a distinct advantage over the 100-yard-zero.

Now, let’s add the 36 yard zero into the mix.

From the muzzle to approximately 42 yards, the 36 yard zero has a slight advantage over the 50 yard zero. From 50 yards out to approximately 235 yards, the 50 yard zero has a distinct advantage over the 36 yards zero. It isn’t until shooting past the distance of approximately 235 yards that the 36 yard zero regains any advantage over the 50 yard zero. Choose your zeroing scheme based on the pertinent facts.

Some reference material. Except where noted, all barrel lengths are 20 inches

Courtesy of zrxc77

M855 25 yard zero

M855 25 meter zero

M855 36 yard vs 100 yard zero

M855

M855 and M193 25 meter zero

M855 and M193 50 yard zero from 16” barrel

M193 25 meter, 50 yard and 100 yard zeros from 16" barrel

100 yard zero

25 meter vs 50 yard zero, M855 from 16” barrel

25 meter vs 50 meter zero , M193 from 16" barrel

M855 300 meter zero

M855 200 meter vs 300 meter zeros

M855 36 yard vs 50 yard zeros

Thanks for posting all of that. Kind of surprised it even needed to be explained.

I set up different rifles, different.

Scoped bolts I tend to 100 yard zero and rely on my range book.

AR carbines are almost always double zeroed because they can be an indoor / outdoor rifle.

The important thing is to actually shoot your rifles no matter what zero you are using. If you are using a double zero you want to confirm both distances, everything between and everything short of your close zero.

[MSW]

Thanks for posting all of that. Kind of surprised it even needed to be explained.

I set up different rifles, different.

Scoped bolts I tend to 100 yard zero and rely on my range book.

AR carbines are almost always double zeroed because they can be an indoor / outdoor rifle.

The important thing is to actually shoot your rifles no matter what zero you are using. If you are using a double zero you want to confirm both distances, everything between and everything short of your close zero.

My “plinking” rifles aka home defense SBRs (under 300 yards) are 50/200 and, like the above gent, my distance-oriented rifles (Tikka 6.5CM & 22” Hbar 5.56 & CLE Hbar) are zeroed at 100 with dope cards.

I might use a 36 if I was required to engage targets at distance, but I’m more likely to need to “fix bayonets” as a civilian, or choose the available tool at the moment since I don’t live in an area where I would be required to shoot 325 yard out bad guy, hence my choices. And, if I did know, Tikka or CLE would be my choice.

YMMV

[ST911]

Me: 1x RDS, 50yd, verifying the ~200 crossover. 1-6x or 8x LPVO, 100yd, dope trued as far as range allows.

The important thing is to actually shoot your rifles no matter what zero you are using. If you are using a double zero you want to confirm both distances, everything between and everything short of your close zero.

This. If you don't actually shoot and know it, it's all just academic.

[HKGuns]

Me: 1x RDS, 50yd, verifying the ~200 crossover. 1-6x or 8x LPVO, 100yd, dope trued as far as range allows.



This. If you don't actually shoot and know it, it's all just academic.

This is how I set mine up as well. I have one more option, my purely hunting rifles are zeroed to MPBR as I find that works best for me in that particular situation.

I verify my hunting rig at the range every year prior to taking it out as it probably wasn't shot off season.

[vicious_cb]

Ok, people are just throwing out their favorite zero like 50/200 without context. I repeat, if you are not using a referencesless reticle like a red dot, you are NOT trying to minimize your max ord. with a cookie cutter 50/200 zero, you are trying to match the particular cartridge to whatever reticle you are using so your reticle marks actually mean something. Which means you are using a ballistic calculator then confirming at the range if your POI is matching the reticle at the desired distances. If your POIs at common distances are just floating in space between your reference marks then there is no point in even having spent money on said reticle when you should have got an red dot magnifier instead.

As ST said, many LPVO reticles are built around a 100 yd zero with the center of the reticle with a particular cartridge and velocity, you may need to zero closer or further depending on how far your gun/ammo combo deviates from the reference cartridge.

[grizzman]

The OP didn't specify what LPVO he's using, nor what type of reticle it uses, so my guess is that he's not looking for information specific to his setup.

Most LPVO reticles incorporate elevation holdover hash marks in MOA, MILs, or BDC, so the MPBR concept generally isn't utilized. If the OP's recicle is just a duplex crosshair, then it's best to treat it like a RDS and determine the appropriate zero based on his expected target distances and size.

[Molon]

The Trijicon Credo HX reticle is for a 50/200 yard zero.


Trijicon Credo HX 1-6x24: A Quick Look





One of Trijicon’s more recent entries into the very crowded low-power variable optic market is the Credo HX 1-6x24. Trijicon produces six different versions of the Credo HX 1-6x24. This article spotlights the version with the bullet-drop compensating “Hunter Holds” reticle for 223 Remington, with the LED red dot; SKU number CRHX624-C-2900020

Trijicon is marketing this optic as a “hunting riflescope,” hence the “Hunter Holds” reticle nomenclature. Despite this optic’s relatively late entry into the LPVO market, it’s gaining favor with the AR-15 defensive shooting crowd; and for good reasons. The Credo HX is not “the best” in any of the relevant metrics. However, for those who prefer a second focal plane LPVO on a defensive rifle and aren't interested in defined ranging capabilities, the Credo HX checks many of the preferred boxes, the least of which is a very reasonable price tag for an optic of this quality.





The Trijicon Credo HX 1-6x24 is not the lightest LPVO in its category, but it’s not the heaviest either. Without a mount or lens covers, the Credo HX has a weight of 1 pound, 2.7 ounces.





The optic is supplied with bikini-style lens covers and a neoprene scope cover. It also comes with a small magnification-ring throw-lever that can be positioned in two different locations on the ring.





The diopter of the ocular lens is adjustable. The ¼ MOA windage and elevation turrets are capped and the turrets can be “zeroed out” by simply pulling up on the adjustment cap, spinning it to the desired location and pushing it back down.






















The bullet-drop compensating reticle on the Credo HX is based on the German #4 reticle. The Credo HX reticle has four stadia lines on the horizontal cross-hair for rudimentary windage and moving-lead hold-offs. The vertical cross-hair has five stadia lines to compensate for bullet-drops from 300 to 700 yards.







The come-ups of the BDC reticle are a damn near perfect match for my 55 grain loads.







A rough check at 50 yards of the BDC come-ups shows that they are just as advertised. Obviously, since this is a second focal plane reticle, those particular bullet drop compensations only apply with the magnification set a 6X.











For those of you who expressed an interest in my target shown above, you can down-load a .pdf file of it here.


Now, for the more ponderous aspect of this short review; the brightness of the red dot. The LED red dot on the Credo HX is powered by a CR2032 battery which is housed in the brightness adjustment turret. The turret has ten brightness settings with an "off" setting in between each of the brightness levels. The battery powered LED red dot of the Credo HX is definitely daylight bright. If I had to make a subjective comparison, to my MK 1 eyes, the brightness of the red dot on the Credo HX is nearly as bright as the second highest brightness setting on the Aimpoint Comp M5. Even in a manipulated scenario with the brightest outdoor ambient lighting I could find (short of looking into the sun), the dot was still slightly visible.

To demonstrate the above comparison, I took a couple of pictures, outdoors, on a cloudless day. The Credo HX was aimed at a reflective, white garage door with the sun shining at the door from approximately 04:30 behind me.

The first picture shown below is a view of an Aimpoint Comp M5 positioned in a shaded area and aimed at the bright white garage door with the brightness setting on the second highest level. (Keep in mind that the 2 MOA dot of the Aimpoint Comp M5 appears at least two times as large as the red dot on the Credo HX in this example.)








The next picture shows the same view, now through the Credo HX set at 1X magnification positioned in the shaded area with the brightness setting on “10”. The illumination of many of the low-power variable optics on the market would be completly washed out in this scanario.








The last pic shows the red dot of the Credo HX aimed at an actual target.







…..

[Sidneyious]

I don’t live in an area where I would be required to shoot 325 yard out bad guy, hence my choices. And, if I did know, Tikka or CLE would be my choice.

YMMV

I thought the same thing till I was using a range finder sitting on my porch looking down the neighborhood.

So I took a 16" upper and made it a 500y upper.

[MSW]

I thought the same thing till I was using a range finder sitting on my porch looking down the neighborhood.

So I took a 16" upper and made it a 500y upper.

That’s why i have a Tikka in 6.5CM & Compass Lake Engineering SAM-R sighted in at 100 yards & DOPE for my handloads in 6.5CM & Black Hills 77gr TMK & DOPE. I’m in suburbia & honestly wish Claymores were an option in the times of civil unrest due to nothing being over 200 yards LOS. Given certain wilding groups tendency to toss Molotovs, I think the right tool isn’t readily available.