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.)



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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.



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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.



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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.


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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.  Choose your zeroing scheme based on the pertinent facts.

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


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Courtesy of zrxc77

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M855 25 yard zero

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M855 25 meter zero

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M855 36 yard vs 100 yard zero

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M855

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M855 and M193 25 meter zero

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M855 and M193 50 yard zero from 16” barrel

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

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100 yard zero

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

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

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M855 300 meter zero

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M855 200 meter vs 300 meter zeros

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M855 36 yard vs 50 yard zeros

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RIBZ

Revised Improved Battlesight Zero

The standard A2 rear sights on an AR-15/M16A2 were designed with elevation settings for 300 to 800 meters.  The Santose Improved Battlesight Zero allows for an elevation setting of 50 yards/200 meters for one of the most all-around useful trajectories obtainable with the 5.56mm/223 Remington cartridge when fired from an AR-15.  

Neither of the above sighting schemes allow for an elevation setting giving you point of aim equals point of impact at 100 yards.  Since 100 yard shooting ranges are some of the most commonly found ranges in the United States and some agencies are promoting the use of a 100 yard zero, it would be useful to have such a setting on our AR-15s.  This can be achieved quite easily with nothing more than a 1/16” allen wrench.  It’s really just a matter of taking the Improved Battlesight Zero one step further.

There is a witness hole on the A2 rear sight base that gives you access to the index screw that you will need to loosen with the 1/16” allen wrench to make the necessary alteration to the elevation drum.  The witness hole lines up with the index screw only when the elevation drum is set to 8/3.  Set your elevation drum on the 8/3 setting and turn the screw counter-clockwise 3 to 4 complete turns.  You don’t want to remove the screw.  You want to loosen it enough to allow the elevation index wheel (the top part of the elevation drum with the numbers on it) and the elevation knob (the bottom part of the elevation drum) to separate and be able to move independently of each other.


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Once you have loosened the index screw, use one hand to hold the allen wrench in place on the screw and with your other hand turn the elevation knob (the bottom part of the elevation drum) 4 clicks clockwise.*  You should see the rear sight base moving up while you do this. The elevation index wheel should not move while you are doing this.  (We really only need to turn the elevation knob 3 clicks clockwise, but by turning it 4 clicks we get a “buffer zone” that keeps the rear sight base from coming into contact with the lower receiver when the sight is moved to the lowest used setting.  This gives you a more consistently repeatable sight setting.)



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Now that you have moved the elevation knob 4 clicks clockwise, taking care to make sure the elevation index wheel has not moved, firmly tighten the index screw.  Starting with the elevation drum at the 8/3 setting, you should easily be able to turn the drum counter-clockwise 3 clicks and see the rear sight base moving down.  (You should be able to turn the elevation drum one more click counter-clockwise for our “buffer zone.”)  You are now ready to head to the shooting range.

As I mentioned earlier, this sighting scheme is really just taking the Improved Battlesight Zero one step further.  Starting with the elevation drum at the 8/3 setting, turn the elevation drum counter-clockwise 3 clicks (8/3, -3).  This is your 100 yard point of aim equals point of impact setting.  From a distance of 100 yards, zero the rifle with the rear sight at this setting (using the small sight aperture).  Do not change this rear sight elevation setting while zeroing. Use the front sight post only to make changes in elevation while zeroing.  

The beauty of the RIBZ sighting scheme is that once you have zeroed the rifle with this method, you will have your 100 yard zero setting and the other settings of the elevation drum remain intact (within the limits of the coarse adjustments of the A2 sights).  If you want to use the Improved Battlesight Zero, simply set the elevation drum to 8/3, -2 and you're good to go.  To use the standard military 300 meter setting, just set the elevation drum to 8/3.  You can also start the zeroing process by obtaining the Santose Improved Battlesight Zero at a distance of 50 yards with the rear sight on the 8/3, -2 setting.   Obviously, slight variations will be encountered depending on the ammunition used and the actual amount of movement with each click of the various sights.  The results will certainly be close enough “for government work.”

When using this sighting method, you may find that once you have set your 100 yard zero, the top of the base of the front sight post is now slightly above the top of the well in the front sight base.  If this happens, the “0.040” taller” front sight post from Bushmaster provides a quick and inexpensive fix.


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100 yard zero (8/3, -3)

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Improved Battlesight Zero (8/3, -2)

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Standard 300 meter zero (8/3)

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* E.T.A.

All click references should be doubled when using detachable carry handle sights.


IBZ  (6/3, -4)



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While the Revised Improved Battlesight Zero is certainly not perfect, here is an example of how well it does work at the distances typically encountered at the public KD ranges in my state.  I zeroed my 20” Colt with A2 sights at 100 yards as described in this thread.  Here is a pic of a 10-shot group from 100 yards.


100 yards, (8/3, -3)


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Next, I packed up my gear and headed to the 50 yard line.  By simply coming up one click on the elevation wheel (8/3, -2), I was in the 10-ring at 50 yards.

50 yards, (8/3, -2)

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Lastly, I moved down to the 25 yard line.  With this sighting scheme, setting the elevation wheel to (8/3, +3) gives me the necessary elevation for 25 yards.  (Again, due to the course adjustment of the AR-15 sights and manufacturing tolerances none of these settings are perfect.)   In fact, if you don't have access to a 100 yard range or you just want to “get on paper” before heading to the 100 yard range to refine the zero, you can zero at 25 yards using this setting.

25 yards, (8/3, +3)

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Here is a down-loadable target in .pdf format that can be used for zeroing 20” uppers with A2 sights at 100 yards using the Revised Improved Battlesight Zero.  The dashed vertical grey lines represent one click of the windage knob.  The dashed horizontal lines represent one click of the FRONT SIGHT POST.



100 yard zeroing target

When printing, you need to have the “page scaling” option in Adobe Reader set to “none” in order for the target to print with the correct dimensions.



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0-2

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There seems to be some confusion around here as to the function of the “0-2” large aperture of the A2 rear sight.  The field manual for M16A1 and M16A2 Rifle Marksmanship states, “The larger aperture, marked 0-2, is used for moving target engagement and during limited visibility.  The unmarked aperture is used for normal firing situations, zeroing and with the elevation knob for target distances up to 800 meters.  The unmarked aperture is used to establish the battlesight zero.”  That’s pretty straightforward.

Using a digital caliper, the diameter of the small aperture of the A2 rear sight measures approximately .070”.  The large (0-2) aperture has a diameter of approximately .200”.  No confusion there.

To use the 0-2 large aperture, simply push forward and down on the small aperture portion of the sight leaf to snap the large, 0-2 aperture up into place.   That couldn’t get much easier.  

The confusion surrounding the use of the 0-2 large aperture seems to stem from a misunderstanding of the amount of elevation change involved when changing from the small aperture to the large aperture.  The small aperture is intended to be zeroed for a 300 meter zero using M855 fired from a 20” barreled M16A2.  The 0-2 large aperture is intended to provide a 200 meter zero, when the small aperture has been properly zeroed with M855 from a 20” barreled M16A2.  If you examine the trajectories of M855 fired from a 20” barreled M16A2 zeroed at 300 meters, and at 200 meters, you will see that the difference in elevation between these two trajectories (and hence the difference in elevation between the small and large apertures) is 2.5 MOA.

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To demonstrate this concept, I fired two 10-shot groups from a 20" Colt AR-15, using the standard A2 iron sights, from the bench at a distance of 50 yards using the small aperture.  I then flipped the rear sight to the 0-2 large aperture and fired another two 10-shot groups (all groups were fired on separate targets.)  The two sets of groups were overlayed on each other to form 20-shot composite groups using RSI Shooting Lab and analyzed to determine the statistical center of their points of impact.

In a perfect world, the groups fired using the 0-2 large aperture would have the center of their points of impact 2.5 MOA (1.25” at 50 yards) below the center of the the points of impact of the groups fired using the small aperture.  The 20-shot composite group formed from the 2 groups fired using the 0-2 large aperture had a center of point of impact 1.01” below the center of point of impact of the 20-shot composite group fired using the small aperture.  1.01” at 50 yards is 2.02 MOA; not exactly 2.5 MOA, but within a half minute of angle and well within my margin of error using the A2 iron sights.  As a side note, the groups fired using the 0-2 large aperture were 144% larger than the groups fired using the small aperture.


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The shifts will definitely be greater with carbines due to the shorter sight radius. I’d like to thank Hallorann for sending me a link to the XS Sights (formerly Ashley Express) website where there is some information that may shed some more light on this subject. I have not experienced this myself and therefore cannot vouch for the validity of the information, but according to XS Sights there are three different A2 rear sight leafs on the market that have different elevation offsets; however, XS Sights does not state which manufacturers/models use which rear sight leafs. (My experience with the A2 sights has been strictly with Colt 20" models and they have all had the 2.5 MOA offset for the 0-2 large aperture, and yes, I drank the Kool-Aid.)

According to XS Sights:

“Comparing some of the rear sights available today there appears to be 3 variations available. The 1st style (and oldest) has a .014 offset. This gives a 2.52 inch shift in point of impact at 100 yards between the two apertures. The 2nd style has a .017 offset, which shifts point of impact 3.06 inches at 100 yards. The 3rd style has a .024 offset giving a 4.36 inch shift in P.O.I.

All of the points of impact shifts shown above are for the standard barrel AR-15/M-16 that has a sight radius of 20 inches. The shorter sight radius (14.5 inches) of the M4 carbine and weapons of similar configuration increase the amount of point of impact shift. The shifts for these shorter sight radius weapons are 3.48, 4.25, 5.96 inches respectively.

The only reason for the various shifts would be for changes in the ammunition used by the military over the course of this weapons employment.”

The last statement in the above quote seems rather odd to me, as M855 still is, and always has been the standard issue ammunition since the adoption of the M16A2. Also, I don't see any particular use for the 3.06 MOA and 4.36 MOA offsets for a 20" barrel. With the small aperture properly zeroed for 300 meters, the 3.06 MOA offsett will produce a 165 yard zero and with the 4.36 MOA offset, the bullet will never cross the line of sight.


20" barrel with M855 zeroed for 300 meters

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Colt Front Sight Posts

Colt has produced at least four different front sight posts for use on their AR-15/M16/M4 series of weapons.  The front sight posts can be roughly categorized according to their basic shape, (square or round) their profile, (straight or tapered) and their height of the post above the "flange", (short or tall.)  The height of the posts are measured from the top of the sight post down to the top of the flange of the sight post.

The sight post with the part number SP64507 has a short, square and straight configuration.  This post has a measured nominal height of approximately 0.270”

SP64507
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Part number SP64665 also has a short and square post, but differs from the above sight post in that it has a tapered shape to it; broader at the base and narrowing at the top.  The measured nominal height of this post is also approximately 0.270”.

SP64665
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Shown below are the square, short/straight and short/tapered sight posts side by side for comparison.

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The sight post associated with the M16/M16A1 series of rifles has a round shape and is also short and tapered.  The part number for this post is SP61706.  It is slightly shorter than the two posts described above with a measured nominal height of approximately 0.260”.

SP61706
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The last sight post is Colt’s tall sight post which has a measured nominal height of approximately 0.300”.  It has a square and straight configuration.  Its part number is SP62447.

SP62447
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Here is a pic with the round sight post and the tall sight post side by side for comparison.

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The original round sight post has five equally spaced notches around the sight post flange for elevation adjustment.  Each notch corresponds to approximately 1 MOA of elevation (when used with a rifle length sight radius).  The other three sight posts all have four elevation notches on their flanges corresponding to approximately 1.25 MOA of evlevation (with the rifle length sight radius).

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"F" Marked Front Sight Base


There is no difference in the overall height of an “F” marked front sight base and a standard front sight base.  The difference between the two front sight bases is the height of the sight “shelf” above the top of the barrel.

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.....

Great info! Thanks again Molon.

Taggity .... to read later when I'm not so freakin tired.

Nice write up ... thanks Molon

Thanks. Another informative post.

This is a sticky worthy thread if I ever seen one.

epic post, thanks

thank you for the great information...

Thanks for another great write molon

Wow, very well put together.

Interesting data.



Using your numbers I get this:

Load Data
~~~~~~~~~

Name: AR15
Ballistic Coeff: 0.259
Bullet Weight: 55
Velocity: 3000
Target Distance: 100
Scope Height: 2.600
Temperature: 59
Altitude: 0

Ballistic Data
~~~~~~~~~~~~~~~
 Range  Elevation  Velocity   Energy     ETA         Drop      Max Y  10mph Wind Deflect
 0 yds   -2.60 in  3000 fps  1099 fpe  0.000 sec    0.00 in  -2.60 in    0.00 in
25 yds   -1.55 in  2907 fps  1032 fpe  0.025 sec    0.12 in  -1.01 in    0.06 in
50 yds   -0.75 in  2816 fps   968 fpe  0.052 sec    0.50 in  -0.91 in    0.28 in
75 yds   -0.23 in  2727 fps   908 fpe  0.079 sec    1.16 in  -0.74 in    0.66 in
100 yds    0.00 in  2640 fps   851 fpe  0.107 sec    2.11 in  -0.49 in    1.19 in
125 yds   -0.08 in  2554 fps   797 fpe  0.136 sec    3.37 in  -0.15 in    1.87 in
150 yds   -0.49 in  2470 fps   745 fpe  0.165 sec    4.95 in   0.29 in    2.71 in
175 yds   -1.25 in  2388 fps   696 fpe  0.196 sec    6.89 in   0.83 in    3.71 in
200 yds   -2.40 in  2307 fps   650 fpe  0.228 sec    9.22 in   1.49 in    4.95 in
225 yds   -3.97 in  2227 fps   606 fpe  0.261 sec   11.97 in   2.28 in    6.40 in
250 yds   -5.98 in  2150 fps   564 fpe  0.296 sec   15.16 in   3.21 in    8.06 in
275 yds   -8.45 in  2073 fps   525 fpe  0.331 sec   18.80 in   4.29 in    9.91 in
300 yds  -11.46 in  1999 fps   488 fpe  0.368 sec   22.98 in   5.55 in   12.03 in
325 yds  -14.86 in  1925 fps   452 fpe  0.406 sec   27.57 in   6.96 in   14.22 in
350 yds  -18.95 in  1853 fps   419 fpe  0.445 sec   32.83 in   8.60 in   16.78 in
375 yds  -23.73 in  1784 fps   389 fpe  0.487 sec   38.79 in  10.48 in   19.69 in
400 yds  -29.24 in  1717 fps   360 fpe  0.530 sec   45.47 in  12.62 in   22.90 in
425 yds  -35.49 in  1652 fps   333 fpe  0.575 sec   52.90 in  15.03 in   26.40 in
450 yds  -42.50 in  1588 fps   308 fpe  0.621 sec   61.08 in  17.72 in   30.16 in
475 yds  -50.27 in  1527 fps   285 fpe  0.669 sec   70.04 in  20.72 in   34.16 in
500 yds  -59.05 in  1468 fps   263 fpe  0.719 sec   80.00 in  24.08 in   38.54 in
525 yds  -68.91 in  1411 fps   243 fpe  0.771 sec   91.03 in  27.85 in   43.30 in
550 yds  -79.99 in  1359 fps   225 fpe  0.825 sec  103.29 in  32.08 in   48.48 in
575 yds  -92.28 in  1309 fps   209 fpe  0.882 sec  116.75 in  36.76 in   54.02 in
600 yds -105.75 in  1261 fps   194 fpe  0.940 sec  131.40 in  41.91 in   59.85 in
625 yds -120.72 in  1217 fps   181 fpe  1.001 sec  147.55 in  47.62 in   66.10 in
650 yds -137.27 in  1178 fps   169 fpe  1.063 sec  165.27 in  53.91 in   72.74 in
675 yds -155.39 in  1142 fps   159 fpe  1.128 sec  184.58 in  60.79 in   79.72 in
700 yds -175.26 in  1109 fps   150 fpe  1.195 sec  205.62 in  68.32 in   87.06 in
725 yds -196.90 in  1080 fps   142 fpe  1.263 sec  228.44 in  76.51 in   94.72 in
750 yds -220.46 in  1054 fps   136 fpe  1.333 sec  253.17 in  85.38 in  102.70 in
775 yds -245.90 in  1030 fps   130 fpe  1.405 sec  279.79 in  94.96 in  110.96 in
800 yds -273.33 in  1009 fps   124 fpe  1.479 sec  308.40 in 105.27 in  119.51 in



Also, let's assume a killzone of 7 inches. In this case, sight in your rifle dead on at 254 yards. Maximum point blank range is 294 yards.

I set up my SHTF carbine with a 50 / 200 yard zero. Here is the print out. Your exact figures may change slightly due to temp, bullet, etc.

Load Data
~~~~~~~~~

Name: 16" SHTF CARBINE
Ballistic Coeff: 0.259
Bullet Weight: 55
Velocity: 2900
Target Distance: 200
Scope Height: 2.600
Temperature: 70
Altitude: 500

Ballistic Data
~~~~~~~~~~~~~~~
 Range  Elevation  Velocity   Energy     ETA         Drop      Max Y  10mph Wind Deflect
 0 yds   -2.60 in  2900 fps  1027 fpe  0.000 sec    0.00 in  -2.60 in    0.00 in
25 yds   -1.18 in  2813 fps   966 fpe  0.026 sec    0.13 in  -1.01 in    0.07 in
50 yds   -0.03 in  2727 fps   908 fpe  0.053 sec    0.54 in  -0.90 in    0.30 in
75 yds    0.82 in  2643 fps   853 fpe  0.081 sec    1.24 in  -0.72 in    0.68 in
100 yds    1.36 in  2561 fps   801 fpe  0.110 sec    2.25 in  -0.45 in    1.20 in
125 yds    1.58 in  2480 fps   751 fpe  0.140 sec    3.59 in  -0.09 in    1.88 in
150 yds    1.45 in  2400 fps   703 fpe  0.171 sec    5.27 in   0.37 in    2.70 in
175 yds    0.93 in  2322 fps   658 fpe  0.202 sec    7.35 in   0.95 in    3.75 in
200 yds   -0.00 in  2245 fps   616 fpe  0.235 sec    9.83 in   1.65 in    5.00 in
225 yds   -1.37 in  2170 fps   575 fpe  0.269 sec   12.75 in   2.49 in    6.46 in
250 yds   -3.18 in  2097 fps   537 fpe  0.305 sec   16.12 in   3.47 in    8.10 in
275 yds   -5.47 in  2024 fps   500 fpe  0.341 sec   19.96 in   4.61 in    9.92 in
300 yds   -8.28 in  1953 fps   466 fpe  0.378 sec   24.33 in   5.92 in   11.97 in
325 yds  -11.63 in  1883 fps   433 fpe  0.417 sec   29.24 in   7.42 in   14.24 in
350 yds  -15.67 in  1816 fps   403 fpe  0.458 sec   34.83 in   9.15 in   16.85 in
375 yds  -20.42 in  1750 fps   374 fpe  0.500 sec   41.13 in  11.12 in   19.77 in
400 yds  -25.90 in  1687 fps   347 fpe  0.544 sec   48.16 in  13.36 in   22.97 in
425 yds  -32.13 in  1625 fps   322 fpe  0.590 sec   55.94 in  15.87 in   26.44 in
450 yds  -39.12 in  1564 fps   299 fpe  0.637 sec   64.49 in  18.67 in   30.14 in
475 yds  -46.89 in  1505 fps   277 fpe  0.685 sec   73.82 in  21.76 in   34.07 in
500 yds  -55.79 in  1450 fps   257 fpe  0.736 sec   84.27 in  25.27 in   38.46 in
525 yds  -65.79 in  1397 fps   238 fpe  0.789 sec   95.82 in  29.18 in   43.20 in
550 yds  -76.99 in  1347 fps   221 fpe  0.844 sec  108.58 in  33.54 in   48.33 in
575 yds  -89.39 in  1299 fps   206 fpe  0.900 sec  122.54 in  38.36 in   53.78 in
600 yds -102.98 in  1254 fps   192 fpe  0.959 sec  137.68 in  43.64 in   59.51 in
625 yds -118.15 in  1212 fps   180 fpe  1.020 sec  154.40 in  49.50 in   65.68 in
650 yds -134.86 in  1175 fps   168 fpe  1.083 sec  172.67 in  55.93 in   72.21 in
675 yds -153.16 in  1140 fps   159 fpe  1.147 sec  192.52 in  62.95 in   79.05 in
700 yds -173.20 in  1109 fps   150 fpe  1.214 sec  214.12 in  70.61 in   86.24 in
725 yds -195.01 in  1080 fps   143 fpe  1.283 sec  237.48 in  78.92 in   93.75 in
750 yds -218.74 in  1056 fps   136 fpe  1.353 sec  262.76 in  87.92 in  101.56 in
775 yds -244.33 in  1033 fps   130 fpe  1.425 sec  289.91 in  97.61 in  109.65 in
800 yds -271.92 in  1012 fps   125 fpe  1.498 sec  319.05 in 108.04 in  118.01 in

Moving Target Lead Data
~~~~~~~~~~~~~~~~~~~~~~~
Range       5 Mph     10 Mph     15 Mph     20 Mph     25 Mph     30 Mph     35 Mph     40 Mph     45 Mph     50 Mph     55 Mph     60 Mph
 0 yds    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft
25 yds    0.19 ft    0.39 ft    0.58 ft    0.77 ft    0.96 ft    1.16 ft    1.35 ft    1.54 ft    1.73 ft    1.93 ft    2.12 ft    2.31 ft
50 yds    0.39 ft    0.78 ft    1.18 ft    1.57 ft    1.96 ft    2.35 ft    2.74 ft    3.14 ft    3.53 ft    3.92 ft    4.31 ft    4.70 ft
75 yds    0.60 ft    1.19 ft    1.79 ft    2.39 ft    2.99 ft    3.58 ft    4.18 ft    4.78 ft    5.38 ft    5.97 ft    6.57 ft    7.17 ft
100 yds    0.81 ft    1.62 ft    2.43 ft    3.23 ft    4.04 ft    4.85 ft    5.66 ft    6.47 ft    7.28 ft    8.09 ft    8.89 ft    9.70 ft
125 yds    1.03 ft    2.05 ft    3.08 ft    4.11 ft    5.13 ft    6.16 ft    7.19 ft    8.21 ft    9.24 ft   10.27 ft   11.29 ft   12.32 ft
150 yds    1.25 ft    2.50 ft    3.75 ft    5.00 ft    6.25 ft    7.50 ft    8.75 ft   10.00 ft   11.25 ft   12.51 ft   13.76 ft   15.01 ft
175 yds    1.48 ft    2.97 ft    4.45 ft    5.93 ft    7.42 ft    8.90 ft   10.39 ft   11.87 ft   13.35 ft   14.84 ft   16.32 ft   17.80 ft
200 yds    1.73 ft    3.45 ft    5.18 ft    6.90 ft    8.63 ft   10.35 ft   12.08 ft   13.81 ft   15.53 ft   17.26 ft   18.98 ft   20.71 ft
225 yds    1.98 ft    3.95 ft    5.93 ft    7.90 ft    9.88 ft   11.86 ft   13.83 ft   15.81 ft   17.78 ft   19.76 ft   21.74 ft   23.71 ft
250 yds    2.23 ft    4.47 ft    6.70 ft    8.94 ft   11.17 ft   13.40 ft   15.64 ft   17.87 ft   20.11 ft   22.34 ft   24.58 ft   26.81 ft
275 yds    2.50 ft    5.00 ft    7.50 ft   10.00 ft   12.50 ft   15.00 ft   17.50 ft   20.00 ft   22.50 ft   25.00 ft   27.50 ft   30.00 ft
300 yds    2.77 ft    5.55 ft    8.32 ft   11.10 ft   13.87 ft   16.65 ft   19.42 ft   22.20 ft   24.97 ft   27.75 ft   30.52 ft   33.30 ft
325 yds    3.06 ft    6.12 ft    9.18 ft   12.24 ft   15.29 ft   18.35 ft   21.41 ft   24.47 ft   27.53 ft   30.59 ft   33.65 ft   36.71 ft
350 yds    3.36 ft    6.71 ft   10.07 ft   13.43 ft   16.79 ft   20.14 ft   23.50 ft   26.86 ft   30.21 ft   33.57 ft   36.93 ft   40.29 ft
375 yds    3.67 ft    7.34 ft   11.01 ft   14.67 ft   18.34 ft   22.01 ft   25.68 ft   29.35 ft   33.02 ft   36.68 ft   40.35 ft   44.02 ft
400 yds    3.99 ft    7.98 ft   11.97 ft   15.97 ft   19.96 ft   23.95 ft   27.94 ft   31.93 ft   35.92 ft   39.92 ft   43.91 ft   47.90 ft
425 yds    4.33 ft    8.65 ft   12.98 ft   17.30 ft   21.63 ft   25.95 ft   30.28 ft   34.61 ft   38.93 ft   43.26 ft   47.58 ft   51.91 ft
450 yds    4.67 ft    9.34 ft   14.01 ft   18.68 ft   23.35 ft   28.02 ft   32.69 ft   37.36 ft   42.03 ft   46.70 ft   51.37 ft   56.04 ft
475 yds    5.02 ft   10.05 ft   15.07 ft   20.09 ft   25.12 ft   30.14 ft   35.16 ft   40.19 ft   45.21 ft   50.23 ft   55.25 ft   60.28 ft
500 yds    5.40 ft   10.79 ft   16.19 ft   21.58 ft   26.98 ft   32.37 ft   37.77 ft   43.16 ft   48.56 ft   53.95 ft   59.35 ft   64.75 ft
525 yds    5.78 ft   11.57 ft   17.35 ft   23.13 ft   28.91 ft   34.70 ft   40.48 ft   46.26 ft   52.04 ft   57.83 ft   63.61 ft   69.39 ft
550 yds    6.19 ft   12.37 ft   18.56 ft   24.74 ft   30.93 ft   37.12 ft   43.30 ft   49.49 ft   55.67 ft   61.86 ft   68.05 ft   74.23 ft
575 yds    6.60 ft   13.21 ft   19.81 ft   26.41 ft   33.01 ft   39.62 ft   46.22 ft   52.82 ft   59.43 ft   66.03 ft   72.63 ft   79.23 ft
600 yds    7.03 ft   14.06 ft   21.09 ft   28.13 ft   35.16 ft   42.19 ft   49.22 ft   56.25 ft   63.28 ft   70.31 ft   77.34 ft   84.38 ft
625 yds    7.48 ft   14.96 ft   22.43 ft   29.91 ft   37.39 ft   44.87 ft   52.35 ft   59.82 ft   67.30 ft   74.78 ft   82.26 ft   89.74 ft
650 yds    7.94 ft   15.88 ft   23.82 ft   31.76 ft   39.70 ft   47.64 ft   55.58 ft   63.52 ft   71.46 ft   79.40 ft   87.34 ft   95.27 ft
675 yds    8.41 ft   16.83 ft   25.24 ft   33.66 ft   42.07 ft   50.49 ft   58.90 ft   67.32 ft   75.73 ft   84.15 ft   92.56 ft  100.98 ft
700 yds    8.90 ft   17.81 ft   26.71 ft   35.62 ft   44.52 ft   53.42 ft   62.33 ft   71.23 ft   80.13 ft   89.04 ft   97.94 ft  106.85 ft
725 yds    9.41 ft   18.81 ft   28.22 ft   37.63 ft   47.03 ft   56.44 ft   65.84 ft   75.25 ft   84.66 ft   94.06 ft  103.47 ft  112.88 ft
750 yds    9.92 ft   19.84 ft   29.76 ft   39.69 ft   49.61 ft   59.53 ft   69.45 ft   79.37 ft   89.29 ft   99.21 ft  109.13 ft  119.06 ft
775 yds   10.45 ft   20.90 ft   31.34 ft   41.79 ft   52.24 ft   62.69 ft   73.14 ft   83.58 ft   94.03 ft  104.48 ft  114.93 ft  125.37 ft
800 yds   10.99 ft   21.97 ft   32.96 ft   43.94 ft   54.93 ft   65.92 ft   76.90 ft   87.89 ft   98.88 ft  109.86 ft  120.85 ft  131.83 ft

This data below is for 1911 pistol shooters. My program forced me to sight in the gun for 50 yards using 230 gn ball ammo.
Notice the slight rock like effect of the pistol bullet compaired to the 556 round.  



ALSO ADDED FOR A KILL ZONE OF 7.00 INCHES, MAXIMUM POINT RANGE IS 96 YARDS. SIGHT IN HANDGUN DEAD ON AT 80 YARDS.

Load Data
~~~~~~~~~

Name: SPEER 230 GN BALL
Ballistic Coeff: 0.195
Bullet Weight: 230
Velocity: 900
Target Distance: 50
Scope Height: 0.250
Temperature: 70
Altitude: 500

Ballistic Data
~~~~~~~~~~~~~~~
 Range  Elevation  Velocity   Energy     ETA         Drop      Max Y  10mph Wind Deflect
 0 yds   -0.25 in   900 fps   414 fpe  0.000 sec    0.00 in  -0.25 in    0.00 in
25 yds    1.27 in   883 fps   398 fpe  0.084 sec    1.36 in   0.24 in    0.14 in
50 yds    0.00 in   867 fps   384 fpe  0.170 sec    5.50 in   1.30 in    0.55 in
75 yds   -4.18 in   851 fps   370 fpe  0.257 sec   12.55 in   3.12 in    1.29 in
100 yds  -11.37 in   836 fps   357 fpe  0.346 sec   22.61 in   5.73 in    2.31 in
125 yds  -21.65 in   822 fps   345 fpe  0.437 sec   35.76 in   9.18 in    3.57 in
150 yds  -35.09 in   808 fps   334 fpe  0.529 sec   52.07 in  13.49 in    5.06 in
175 yds  -51.82 in   795 fps   323 fpe  0.622 sec   71.68 in  18.70 in    6.81 in
200 yds  -71.96 in   782 fps   312 fpe  0.717 sec   94.69 in  24.87 in    8.83 in
225 yds  -95.74 in   769 fps   302 fpe  0.814 sec  121.35 in  32.07 in   11.20 in
250 yds -123.26 in   757 fps   293 fpe  0.912 sec  151.74 in  40.34 in   13.88 in
275 yds -154.61 in   745 fps   283 fpe  1.012 sec  185.96 in  49.72 in   16.86 in
300 yds -189.86 in   733 fps   275 fpe  1.114 sec  224.08 in  60.24 in   20.11 in
325 yds -229.08 in   722 fps   266 fpe  1.217 sec  266.17 in  71.94 in   23.61 in
350 yds -272.33 in   711 fps   258 fpe  1.322 sec  312.30 in  84.85 in   27.35 in
375 yds -319.66 in   700 fps   250 fpe  1.428 sec  362.50 in  99.00 in   31.32 in
400 yds -371.27 in   689 fps   242 fpe  1.535 sec  416.99 in 114.46 in   35.55 in
425 yds -427.67 in   678 fps   235 fpe  1.645 sec  476.26 in 131.39 in   40.16 in
450 yds -488.96 in   668 fps   228 fpe  1.756 sec  540.42 in 149.84 in   45.13 in
475 yds -555.24 in   658 fps   221 fpe  1.870 sec  609.57 in 169.85 in   50.45 in
500 yds -626.60 in   648 fps   214 fpe  1.985 sec  683.80 in 191.46 in   56.09 in
525 yds -703.10 in   638 fps   208 fpe  2.102 sec  763.18 in 214.73 in   62.04 in
550 yds -784.84 in   628 fps   201 fpe  2.221 sec  847.79 in 239.70 in   68.28 in
575 yds -871.87 in   619 fps   195 fpe  2.342 sec  937.70 in 266.40 in   74.80 in
600 yds -964.26 in   609 fps   190 fpe  2.464 sec 1032.95 in 294.87 in   81.59 in
625 yds-1063.37 in   600 fps   184 fpe  2.588 sec 1134.94 in 325.53 in   88.90 in
650 yds-1166.56 in   591 fps   178 fpe  2.713 sec 1241.00 in 357.64 in   96.18 in
675 yds-1276.44 in   582 fps   173 fpe  2.840 sec 1353.75 in 391.99 in  103.90 in
700 yds-1393.13 in   573 fps   168 fpe  2.970 sec 1473.31 in 428.62 in  112.07 in
725 yds-1516.74 in   564 fps   163 fpe  3.102 sec 1599.80 in 467.60 in  120.65 in
750 yds-1647.37 in   556 fps   158 fpe  3.237 sec 1733.30 in 508.98 in  129.63 in
775 yds-1785.13 in   547 fps   153 fpe  3.373 sec 1873.93 in 552.84 in  138.99 in
800 yds-1930.09 in   539 fps   148 fpe  3.512 sec 2021.77 in 599.21 in  148.71 in

Moving Target Lead Data
~~~~~~~~~~~~~~~~~~~~~~~
Range       5 Mph     10 Mph     15 Mph     20 Mph     25 Mph     30 Mph     35 Mph     40 Mph     45 Mph     50 Mph     55 Mph     60 Mph
 0 yds    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft    0.00 ft
25 yds    0.62 ft    1.23 ft    1.85 ft    2.47 ft    3.08 ft    3.70 ft    4.32 ft    4.93 ft    5.55 ft    6.17 ft    6.78 ft    7.40 ft
50 yds    1.25 ft    2.49 ft    3.74 ft    4.98 ft    6.23 ft    7.47 ft    8.72 ft    9.96 ft   11.21 ft   12.45 ft   13.70 ft   14.94 ft
75 yds    1.89 ft    3.77 ft    5.66 ft    7.55 ft    9.44 ft   11.32 ft   13.21 ft   15.10 ft   16.98 ft   18.87 ft   20.76 ft   22.65 ft
100 yds    2.54 ft    5.08 ft    7.62 ft   10.16 ft   12.70 ft   15.24 ft   17.78 ft   20.32 ft   22.86 ft   25.41 ft   27.95 ft   30.49 ft
125 yds    3.20 ft    6.41 ft    9.61 ft   12.82 ft   16.02 ft   19.23 ft   22.43 ft   25.63 ft   28.84 ft   32.04 ft   35.25 ft   38.45 ft
150 yds    3.88 ft    7.75 ft   11.63 ft   15.51 ft   19.39 ft   23.26 ft   27.14 ft   31.02 ft   34.90 ft   38.77 ft   42.65 ft   46.53 ft
175 yds    4.56 ft    9.12 ft   13.68 ft   18.25 ft   22.81 ft   27.37 ft   31.93 ft   36.49 ft   41.05 ft   45.61 ft   50.18 ft   54.74 ft
200 yds    5.26 ft   10.51 ft   15.77 ft   21.03 ft   26.28 ft   31.54 ft   36.80 ft   42.06 ft   47.31 ft   52.57 ft   57.83 ft   63.08 ft
225 yds    5.97 ft   11.93 ft   17.90 ft   23.87 ft   29.83 ft   35.80 ft   41.77 ft   47.73 ft   53.70 ft   59.67 ft   65.63 ft   71.60 ft
250 yds    6.69 ft   13.38 ft   20.07 ft   26.76 ft   33.45 ft   40.14 ft   46.83 ft   53.52 ft   60.21 ft   66.90 ft   73.58 ft   80.27 ft
275 yds    7.42 ft   14.85 ft   22.27 ft   29.70 ft   37.12 ft   44.55 ft   51.97 ft   59.40 ft   66.82 ft   74.25 ft   81.67 ft   89.10 ft
300 yds    8.17 ft   16.34 ft   24.51 ft   32.68 ft   40.86 ft   49.03 ft   57.20 ft   65.37 ft   73.54 ft   81.71 ft   89.88 ft   98.05 ft
325 yds    8.93 ft   17.86 ft   26.78 ft   35.71 ft   44.64 ft   53.57 ft   62.50 ft   71.43 ft   80.35 ft   89.28 ft   98.21 ft  107.14 ft
350 yds    9.70 ft   19.39 ft   29.09 ft   38.78 ft   48.48 ft   58.17 ft   67.87 ft   77.56 ft   87.26 ft   96.95 ft  106.65 ft  116.34 ft
375 yds   10.47 ft   20.94 ft   31.41 ft   41.89 ft   52.36 ft   62.83 ft   73.30 ft   83.77 ft   94.24 ft  104.72 ft  115.19 ft  125.66 ft
400 yds   11.26 ft   22.52 ft   33.78 ft   45.04 ft   56.29 ft   67.55 ft   78.81 ft   90.07 ft  101.33 ft  112.59 ft  123.85 ft  135.11 ft
425 yds   12.06 ft   24.12 ft   36.19 ft   48.25 ft   60.31 ft   72.37 ft   84.44 ft   96.50 ft  108.56 ft  120.62 ft  132.68 ft  144.75 ft
450 yds   12.88 ft   25.76 ft   38.64 ft   51.52 ft   64.40 ft   77.28 ft   90.16 ft  103.04 ft  115.93 ft  128.81 ft  141.69 ft  154.57 ft
475 yds   13.71 ft   27.43 ft   41.14 ft   54.85 ft   68.57 ft   82.28 ft   95.99 ft  109.71 ft  123.42 ft  137.13 ft  150.84 ft  164.56 ft
500 yds   14.56 ft   29.12 ft   43.68 ft   58.24 ft   72.80 ft   87.36 ft  101.91 ft  116.47 ft  131.03 ft  145.59 ft  160.15 ft  174.71 ft
525 yds   15.42 ft   30.84 ft   46.25 ft   61.67 ft   77.09 ft   92.51 ft  107.93 ft  123.35 ft  138.76 ft  154.18 ft  169.60 ft  185.02 ft
550 yds   16.29 ft   32.58 ft   48.87 ft   65.16 ft   81.45 ft   97.74 ft  114.03 ft  130.32 ft  146.61 ft  162.89 ft  179.18 ft  195.47 ft
575 yds   17.17 ft   34.34 ft   51.52 ft   68.69 ft   85.86 ft  103.03 ft  120.21 ft  137.38 ft  154.55 ft  171.72 ft  188.90 ft  206.07 ft
600 yds   18.07 ft   36.13 ft   54.20 ft   72.27 ft   90.33 ft  108.40 ft  126.46 ft  144.53 ft  162.60 ft  180.66 ft  198.73 ft  216.80 ft
625 yds   18.98 ft   37.96 ft   56.95 ft   75.93 ft   94.91 ft  113.89 ft  132.87 ft  151.86 ft  170.84 ft  189.82 ft  208.80 ft  227.79 ft
650 yds   19.90 ft   39.79 ft   59.69 ft   79.58 ft   99.48 ft  119.38 ft  139.27 ft  159.17 ft  179.07 ft  198.96

And this has what to do with a AR15 Zeros and Trajectories topic?

Notice the slight rock like effect of the pistol bullet compared to the 556 round.

Molon is being a gentleman and putting up some very good information. For some, this information is old school, however others are new to the black rifle. I love charts and figures and can go toe to toe with anyone on charts for 20-30 pages, if you what me too. In my first post, I in fact added to his charts with additional information.

For entertainment, some people own handguns. I was only adding a little extra information on the differences of handgun bullets against rifle bullets.

Absolutely. Molon should try to break these long posts up into smaller segments, each with one major point. But this does lay it out there for newbies as to sighting in, the trajectory, etc.

Thanks, for  another great post.

Thanks Molon!

This is why I zero at 50 yards.



I shoot XM193 from a 16" carbine. I wanted the flattest trajectory possible out to 200 yards. In most real world civi situations I feel that is the farthest I'd be justified in engaging. Weather it's a Katrina or zombie scenario. For anything farther I know my holds out to 500. But at that kind of distance I'd opt to GTFO if at all possible rather than engage.

I also feel 50 yrd is is ideal for carbines. With a slight hold over you can shoot 300 yrds all day long and be in the kill zone.

From point blank to about 270 yards your within 7 inches. Good enough for me.

updated

updated

Awsome boatload of information!





I have never cared for 25 yard/ 300yard BZO schemes. It seems to me that the margin of error in estimating the center of a grouping at 25 yards multiplied times 12 to project it out to 300 yards is just too much margin of error.





I really like the Santose 50/200 yard BZO. That is my default standard BZO since I only have access to a range with 25/50/100 yard known distances.





For my iron sights, Eotech, and Aimpoint sighting systems, I go with the 50 yard zero, knowing that I'll be good out to 200 yards in any reasonable self defense or SHTF  scenario.





On rifles/carbines where I have a Trijicon ACOG mounted, I go with the 50 yard zero on the BUIS and 100 yard zero on the ACOG to preserve the bullet drop scale built into the reticle.
 

What ballistic program generated the graphs?

Bob

Awesome right up. I'd been looking for additional 50 yd validation and this appears to confirm it for me.

This should be     T A C K E D!

ETA: this is an excellent primer for new shooters wanting to learn how to zero their irons. Questions on this topic get asked a lot...Molon's write-up essentially puts to rest any disagreement.

Awesome!

Oehler's Ballistic Explorer.

If I use a 50 yard zero with a 14.5" barrel, M193 and a Matech BUIS, where would be the best notch on the sight to use when I zero it?  My guess would be "200" yards but would the rest of the holdovers still work?

It's also interesting to see that past 600 yards, the 45acp carries more energy than the 55 gr round. :) Of course, the heavy weight helps but don't expect to hit anything beyond a prayer. haha

I wish i could understand greek

Free Online Greek to English Translator

since im a noob to scopes and i got one in the mail on the way. if i zero it dead on at 50 yards i will be 1.5 high at 100 yards? correct me if im wrong all this stuff is new to me im just a blaster and pray and spray guy lol.

Good stuff.  All technical differences in ammo, barrel length, "zero" go away if you actually shoot some and figure out your DOPE.  I guess if you're fielding an army of your own, then well the details might actually matter.  Or are lazy... or too cheap to shoot... or a crappy shot...

Hell, if you shoot a bunch of different ammo and 3-4 AR's, it all gets convoluted enough to almost be impossible to track all the DOPE data in any form that's quickly useful.

More and more, I'm lead to sticking with one gun...

Cool. Is there somewhere I can get info like this on the 6.8?

Have you been to 68forums.com?

I guess I should have thought of that

Hey Molon, have you any data or tested PMC X-TAC 5.56x45 62grn SS109?

No.  Maybe I'll pick some up for the "spring session."

Wow.. Why they don't give you a free Lifetime membership is beyond me.. you have more then earned it with your posts... Well done...

This is just a guess, and I'll obviously defer to the smart guys here...but I think for .223, the 50 yard equivalent is 200 meters, not yards. (50 yard zero is on at 200 meters, or on at around 220 yards)  You may have meant to say meters, and if I'm not mistaken, the Matech is set up for meters anyway.  I believe the matech was calibrated for a 14.5 inch sight radius.  Assuming this is correct, then if you use 50/200 and have it set on 200, then the remaining calibrations should be very close. I think what would change this however, is if you mount the matech on a 20 inch sight radius, (I realize you said 14.5) my guess is they would be off.  

Thanks for the reply.  I had started a thread about this question which I coulda swore you were in too.  Anyways I did zero it for 50/200 with it set on the 200 yd mark.  I haven't had the chance to shoot it yet at 300 to confirm but hopefully soon.  Again thanks for the info.

What is the cross over point for a 20" A2 rifle that is zeroed at 25 yards?

Also, what is the width of a standard A2 front sight post of a 20" rifle in terms of MOA?  I know the M14 front sight can be used as a range finder, and is 12 MOA wide with rack grade sights and standard rifle configuration.  What is it for the AR?

I was at the range today, and out of 150 rounds fired, I never hit above the bullseye.  I was firing with a sling and standing.  The target was 25 yards away.  I was using 55 gr Fiocchi and Remington .223 which I assume flies similar to M193...

My groups averaged 3" low at 25 yards.  

What do I need to do to my front site to get a 100yd zero?  I don't have elevation rear site adjustments on my M&P15T.  It looks like I should be about 1.5" low at 25 yards with a 100 yard zero based on the charts I see here.  Is that correct?

Freefloater, you say you want a 100 yard zero but you describe wanting to hit center of the target at 25 yards.  If you want POA/POI at 25, this will be similar to the Army's old fashioned 25 meter zero, but it will not be on target at 100 yards.  You know at 25 you also have to deal with "height over bore" which is a little over 2 inches.  (aim high)

I don't want to hit center at 25yd.  I would like to know how to adjust the front site so that I will have a 100yd  zero given that I am about 3in low at 25yd now. And I also wanted to confirm that I should be about 1.5in low (at 25yd) once adjusted.  Sorry if I did not make this clear in my other post.

Out of your S&W M&P15, Remington 55gr FMJ ammo should give you 2,875fps +/- 50 fps.

Yes, a 100 yard zero would be ~1.5" low at 25 yards.

What sights are you using, Troy or MagPul?

tag

Just wanted to say thanks for the breadcrumbs.Once i get most of the pieces of my brain picked up and put back together (it exploded about a half hour ago). this is going to be a goldmine.  I have always been one of THOSE guys who got pissed off and wouldn't use the toaster until could get my head around  the WHY  of the HOW.  So yeah, I coulda just asked somebody at the range, hey can you zero this for me?  But when you are by yourself, and it's just you and the things in your head, you really need to know WHY it's broken, and that will lead you to the HOW of fixing it.

So thanks for taking the time to teach us.  There are those of us noobs who are here for knowledge, and not just for the gadgets and flash.

Tag

Thanks for this very informative article. I have a Bushmaster M4A3 which I like to shoot open sights, I have some questions I'd like to ask. Because of the detachable handle, the A2 sight has 1/2 MOA clicks, which will mean I need to "double" the clicks when tweaking the rearsight? So, for my 100yard zero, that would be the (6/3, -6), correct? You mention setting the elevation drum to 8/3 for 300yards, in my case, if I zero for a 100yds, does that mean I can just return the drum to the 6/3 setting on my rifle and shoot POA, POI at 300yds? Thanks in advance. :)

Is this for 5.56 bc I don't think I am following........with a 25 yard zero your POI will be ~1.3 higher than your POA  @ 250 yards while a 50 yard zero will result in a POI ~5" lower than your POA.  I  know that the Army at 1 point used the 25m zero.  At 100yards the round will rise ~3" from your POA while it is a .5" rise with the 5 yard zero...so it is really a personal preference thing with the zero...i don't see the 50 being any better than the 25 or vica versa....definitely wouldn't do a 100 tho.

Where are you getting your numbers?

With M-193 and a 16" barrel (MV of 3,075fps +/- 25 fps):
A 50yd Zero will be, roughly, an inch high at 200 yds and under 2 inches low at 250yds.
A 25yd Zero will be, roughly, 10 inches high at 200 yds and 250yds.