View Full Version : AR-15 Zeros and Trajectories
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.)
https://www.ar15.com/media/mediaFiles/28568/100_yard_zero_data_01-1301858.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/positive_elevation-1301877.gif
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.
https://www.ar15.com/media/mediaFiles/28568/negative_elevation-1301880.gif
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.
https://www.ar15.com/media/mediaFiles/28568/absolute_value_of_poi_from_poa_02-1301881.jpg
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
https://www.ar15.com/media/mediaFiles/28568/trajectory_with_sight_illustration_from_-1301869.jpg[size=2]Courtesy of zrxc77[/size=2]
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M855 25 yard zero
https://www.ar15.com/media/mediaFiles/28568/M855_25_yard_zero_from_20_inch_barrel_-1301862.jpg
M855 25 meter zero
https://www.ar15.com/media/mediaFiles/28568/M855_25_meter_zero_from_20_inch_barrel_0-1301861.jpg
M855 36 yard vs 100 yard zero
https://www.ar15.com/media/mediaFiles/28568/M855_36_vs_100_yard_zeros_20_inch_barrel-1301863.jpg
M855
https://www.ar15.com/media/mediaFiles/28568/25_meter_zero_versus_300_meter_zero_02-1301913.jpg
M855 and M193 25 meter zero
https://www.ar15.com/media/mediaFiles/28568/m855_and_m193_25_meter_zero_from_20_inch-1301865.jpg
M855 and M193 50 yard zero from 16” barrel
https://www.ar15.com/media/mediaFiles/28568/M855_vs_M193_16_inch_barrel-1301924.jpg
M193 25 meter, 50 yard and 100 yard zeros from 16" barrel
https://www.ar15.com/media/mediaFiles/28568/m193_from_16_inch_barrel_25_50_and_100_z-1301860.jpg
100 yard zero
https://www.ar15.com/media/mediaFiles/28568/m855_and_m193_100_yard_zero_from_20_inch-1301867.jpg
25 meter vs 50 yard zero, M855 from 16” barrel
https://www.ar15.com/media/mediaFiles/28568/50_yard_versus_25_meter_zero_with_M855_f-1301857.jpg
25 meter vs 50 meter zero , M193 from 16" barrel
https://www.ar15.com/media/mediaFiles/28568/50_yard_versus_25_meter_zero_with_M855_f-1301857.jpg
M855 300 meter zero
https://www.ar15.com/media/mediaFiles/28568/300_meter_zero_02-1301859.jpg
M855 200 meter vs 300 meter zeros
https://www.ar15.com/media/mediaFiles/28568/M855_200_meter_vs_300_meter_zero_with_20-1301864.jpg
M855 36 yard vs 50 yard zeros
https://www.ar15.com/media/mediaFiles/28568/36_yard_vs_50_yard_zero_from_20_inch_bar-1301856.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/index_screw_access_01-1301950.jpg
https://www.ar15.com/media/mediaFiles/28568/index_screw_access_02-1301951.jpg
https://www.ar15.com/media/mediaFiles/28568/allen_wrench_01-1301956.jpg
https://www.ar15.com/media/mediaFiles/28568/allen_wrench_00-1301955.jpg
https://www.ar15.com/media/mediaFiles/28568/index_screw_02-1301960.jpg
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.)
https://www.ar15.com/media/mediaFiles/28568/colt_rear_sight_diagram_03-1301972.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/front_sight_posts2-1301973.jpg
100 yard zero (8/3, -3)
https://www.ar15.com/media/mediaFiles/28568/100_yard_setting_01-1301970.jpg
https://www.ar15.com/media/mediaFiles/28568/100_yard_setting_02-1301971.jpg
https://www.ar15.com/media/mediaFiles/28568/100_yard_zero_01-1301976.jpg
Improved Battlesight Zero (8/3, -2)
https://www.ar15.com/media/mediaFiles/28568/IBZ_setting_01-1301980.jpg
https://www.ar15.com/media/mediaFiles/28568/IBZ_setting_02-1301981.jpg
https://www.ar15.com/media/mediaFiles/28568/improved_battle_sight_zero_01-1301982.jpg
Standard 300 meter zero (8/3)
https://www.ar15.com/media/mediaFiles/28568/300_meter_zero_01-1301989.jpg
* E.T.A.
All click references should be doubled when using detachable carry handle sights.
IBZ (6/3, -4)
https://www.ar15.com/media/mediaFiles/28568/carry_handle_02-1301992.jpg
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)
https://www.ar15.com/media/mediaFiles/28568/example_100_yards_01-1302002.jpg
https://www.ar15.com/media/mediaFiles/28568/Colt_A2_HBAR_03_framed_02-1301999.jpg
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)
https://www.ar15.com/media/mediaFiles/28568/example_50_yards_01-1302001.jpg
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)
https://www.ar15.com/media/mediaFiles/28568/example_25_yards_01-1302000.jpg
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 (http://www.box.net/shared/static/zob0fj4zlb.pdf)
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.
https://www.ar15.com/media/mediaFiles/28568/A2_sight_zero_target_02-1302017.jpg
0-2
https://www.ar15.com/media/mediaFiles/28568/large_aperture_01_colored_pencil-1302021.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/small_versu_large_aperture_trajectories-1302023.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/rifle9_resized2-1302022.jpg
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
https://www.ar15.com/media/mediaFiles/28568/20_inch_barrel_offsets-1302051.jpg
Colt Front Sight Post Primer
Colt currently offers four different front sight posts for use on their AR-15/M16 family of weapons. The front sight posts can be categorized according to their basic shape, (square or round) their profile, (straight or tapered) and their height, (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 nominal height of 0.270”
SP64507
https://www.ar15.com/media/mediaFiles/28568/short_straight_front_sight_post_01_resiz-1302034.jpg
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 height of this post is also 0.270”.
SP64665
https://www.ar15.com/media/mediaFiles/28568/short_tapered_sight_post_01_resized-1302035.jpg
Shown below are the square, short/straight and short/tapered sight posts side by side for comparison.
https://www.ar15.com/media/mediaFiles/28568/short_straight_and_tapered_sight_posts_0-1302037.jpg
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 height of 0.260”.
SP61706
https://www.ar15.com/media/mediaFiles/28568/round_front_sight_post_01_resized-1302040.jpg
The last sight post is Colt’s tall sight post which has a nominal height of 0.300”. It has a square and straight configuration. Its part number is SP62447.
SP62447
https://www.ar15.com/media/mediaFiles/28568/colt_tall_front_sight_post_01_resized-1302038.jpg
Here is a pic with the round sight post and the tall sight post side by side for comparison.
https://www.ar15.com/media/mediaFiles/28568/colt_tall_post_and_round_post_01_resized-1302039.jpg
The original round sight post has five equally spaced notches around the sight post flange for elevation adjustment. Each notch corresponds to 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 1.25 MOA of evlevation.
https://www.ar15.com/media/mediaFiles/28568/elevation_notches_on_front_sight_posts_0-1302042.jpg
Bushmaster makes a front sight post that has a nominal height of 0.310”.
https://www.ar15.com/media/mediaFiles/28568/front_sight_posts2_1_-1302043.jpg
"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 only difference between the two front sight bases is the height of the sight “shelf” above the top of the barrel.
https://www.ar15.com/media/mediaFiles/28568/F_front_sight_base_01-1302046.jpg
https://www.ar15.com/media/mediaFiles/28568/F_front_sight_base_02-1302047.jpg
.....
genegoesfast
10-28-10, 10:21
Wow, great posts!
Very nice and very well illustrated!
The 50/200 zero is always a common thought/mistake. People often accept it as gospel when in reality, your zero could be 188, 195, 210, etc. Most folks do not realize this because they cannot shoot their guns out to 200yds.
C4
excellent post. thank you for your very detailed and time consuming research. this is a true resource and one of the reasons I come to m4c. I nominate this for inclusion in the "Knowledge Based Threads".
Shown below are the square, short/straight and short/tapered sight posts side by side for comparison.
http://www.box.net/shared/static/ym1n1ar5e5.jpg
What are the intended uses for a square front sight post vs one that is tapered?
Great info!!
Thanks Molon, excellent information as usual!
pistolman1974
10-28-10, 19:36
I've got a question, I already had my 20" ar 15 zeroed with the Santos method so all I did was add 4 more clicks. ( 6/3 detachable carry handle with half clicks). Theoretically, should I have to change the elevation on the front site despite being on target at 50yds?
Rmplstlskn
10-28-10, 19:56
Molon, you should write a book! Or someone should hire you to write a book...
With the information you provide, as well as the excellent photos, it would be a good seller I believe...
Rmpl
Molon, you should write a book!
Rmpl
;)
http://www.box.net/shared/static/dzt2hes8h8.jpg
Very nice and very well illustrated!
The 50/200 zero is always a common thought/mistake. People often accept it as gospel when in reality, your zero could be 188, 195, 210, etc. Most folks do not realize this because they cannot shoot their guns out to 200yds.
C4
I don't have access to a range longer than 100 yards. Can someone tell me what the corresponding long range zero would be for Hornady TAP Practice 75 gr. zeroed at 50 yards from a 16" barrel?
also, can someone tell me why a 100 yard zero is popular with some SME's?
kaltesherz
10-28-10, 20:56
Awesome! But where's the 75 gr data?
(sorry, I had to ask...)
Heavy Metal
10-28-10, 20:58
Molon,
The quality of your work never ceases to amaze me.
Do you perchance do technical writing for a living?
You should write a book and get Stickman to do your photography.
What are the intended uses for a square front sight post vs one that is tapered?
The tapered flat sided post is Colt's M4 front sight post... and my favorite for carbean shooting. I read somewhere that it was to allow a better visual on your target.
GREAT stuff as usual Molon:D
BlueOvalFan
10-30-10, 04:10
Excellent post; very informative and detailed. My head is spinning from all the choices I need make in setting up my middies.
Well done...
Another outstanding post as usual. Thanks, again for all of the time and effort that you put into your posts. They are of great value to us.
Awesome! But where's the 75 gr data?
(sorry, I had to ask...)
I didn't want this thread to get too complicated, so I just used the ubiquitous M193 and M855 for examples. I'll post another thread with reams of 75 grain data.
.....
Though you (and everyone else) already know this: great thread.
Fantastic explanation..... Breaks it down so it's easier to understand.
Thanks for doing this! Great help to some of us that aren't as sharp as others..... ;)
I'm still waiting for the "Molon Manual" to hit the stores;)
I appreciate the fact that you are keeping this thread going. I zero at 50 yards, then make minute adjustments at 200 yards. Out of my carbine, I can raise the rear sight 3 clicks and be dead on at 300 yards. With the 200 yard zero, I just hold and shoot from 20 yards to 225 yards.
Thanks for having this a sticky. It will help at the range this weekend.
This is killing me.
Anyone else have a problem with Molon's pics not showing up? They don't show up on here or on TOS. I have tried Firefox and IE, including the usual cache and cookie clears. It looks like they are hosted at www.box.net but I have no idea why they don't show...
Cameron
RogerinTPA
12-13-10, 19:29
No issues with viewing Molon's charts at all on 3 separate browsers.
This is killing me.
Anyone else have a problem with Molon's pics not showing up? They don't show up on here or on TOS. I have tried Firefox and IE, including the usual cache and cookie clears. It looks like they are hosted at www.box.net but I have no idea why they don't show...
Cameron
Molon's pictures showed up when I opened the thread. But, I am not a computer person and have no idea why you would not be able to view them. I am a weapons person and agree with his post.
Molon's pictures showed up when I opened the thread. But, I am not a computer person and have no idea why you would not be able to view them. I am a weapons person and agree with his post.
:D Now that's funny.
swampfox1975
12-24-10, 19:34
Very informative info and I am taking this to the range tommorow. I usually shoot 62 gr out of my 16" m4. I will see how this stacks up against a 20".
RockKrawler
12-26-10, 18:32
I will be taking a coupe of new shooters to the range soon,and will use this as a visual tutorial of the proper method for sight adjustment.
Very well written,excellent job.
Thanks,
RK
Well done. Well done, indeed. Thanks....
9Y
Great thread; will refer to it often when I can finally afford an AR.
BTW: Woot, first post :D
Thanks for the thread. Slowly trying to intake all the useful info.
Thanks for the thread. Slowly trying to intake all the useful info.
Yes, thanks much for so well illustrating and explaining the flexibilty we (USMC) tried to build into the A2's rear sight back in 1983. Unfortunately, much of that was lost due to the Operator's Manual being limited to one basic "fits all" procedure; and the concrete being dried on so many 25 meter ranges common in those days.
Excellent post!! Thank you for the valuble info. I have already read it a couple of times and am applying it to my detachable carry handle sight base. Now I will have to head out to the range.
Will removing the detachable carry handle affect the zero once it is set??
I have a red dot coming in the mail (aimpoint comp M2) and will mount it when it arrives. I am a newbie to red dots an am wondering if the method for zero is different.
Molon,
like the above poster,
I am using a RDS. I do not get anything like the 50/200 IBZ. Granted, I am using a 10.5" SBR w/ 69gr handloads. However, I zero at 50yds, and even at 100 yards, I am seeing an approx 3-4" drop. At 200yds, I was about 6" low. Does the IBZ not apply to a RDS since one is not looking thru the rear aperature to the front?
TIA, and thanks for all your helpfuls posts. Truly appreciated.
This is killing me.
Anyone else have a problem with Molon's pics not showing up? They don't show up on here or on TOS. I have tried Firefox and IE, including the usual cache and cookie clears. It looks like they are hosted at www.box.net but I have no idea why they don't show...
Cameron
Are you running Zone Alarm or any other Browser Security Program? I checked Zone Alarm is blocking www.box.net as it is a known site for distributing spyware.
Are you running Zone Alarm or any other Browser Security Program? I checked Zone Alarm is blocking www.box.net as it is a known site for distributing spyware.
Thanks I am!!! I will check Zone Alarm now.
Cameron
Edited to add: Turned Zone Alarm off and the pics show up. Thanks for your help. Now I have to figure out how I can make ZA stop blocking box.net
handlebar1980
02-07-11, 17:25
Fantastic explanation..... Breaks it down so it's easier to understand.
Thanks for doing this! Great help to some of us that aren't as sharp as others..... ;)
great job, great job
sgtkracker83
02-13-11, 18:52
does anyone know the best way to zero an EOTech 512 series for a M4 platform. Haven't done it in years and forgot how. Any help would be appricated.
Molon,
Since you have more rifles and carbines than I do and a chronograph, could you verify that Speer Gold Dot 64gr out of a 16" barrel has a proper 200yd zero when zeroed at 50yds? I've tried hitting the 200yd plates at my local range but can't do it with either irons or with my Micro H-1.
Specs for Gold Dot 64gr is 3000fps IIRC, but that's obviously out of a 24" loose chamber spec bolt action test barrel.
Th3Revreant
02-14-11, 11:55
Thought this might assist in getting a better m4 zero in low light conditions or persons who have a hard time seeing the target. PM me with your email if you would like the file so you can print and use this target.
http://i705.photobucket.com/albums/ww58/reaperpaintball08/M4SightinModified.jpg
If you want to truly zero for both 50m and 200m, you should zero at 200m because small errors of zero at 50m will be magnified at 200m..don't fool yourself that just cause you zeroed at 50m you will be hitting at 200m!
does anyone know the best way to zero an EOTech 512 series for a M4 platform. Haven't done it in years and forgot how. Any help would be appricated.
I like to start off @ 25yards. I shoot 5 round groups at a 1" pasty/square or other similar aiming point. Checking my point of impact between groups, I then adjust the Eotech or Aimpoint to bring my point of impact directly 1.5" below my point of aim at 25yards.
I then go back to 100 yards and make any final adjustments needed to bring my point of aim and my point of impact together at 100 yards. I again shoot 5 round groups and then make adjustment between groups. *Each adjustment click to the Eotech = 1/2" @ 100yds.
Molon,
Any idea what the hold over at 500 & 600yds is with a 100 yard zero?
greyman556
03-04-11, 09:28
This is really helpful article. Thanks!
RogerinTPA
03-04-11, 15:04
If you want to truly zero for both 50m and 200m, you should zero at 200m because small errors of zero at 50m will be magnified at 200m..don't fool yourself that just cause you zeroed at 50m you will be hitting at 200m!
It works for me on 4 ARs. The zero is pretty damn close. Maybe within 1/2 inch to 1 1/2 inch off (higher) from my observations, using Wolf 62 grain HP and FMJ. They would still be A zone/CNS hits. Close enough for me. Try the 50 yard zero, then see what you get at 200. You will be pleasantly surprised. What Molon has posted about the 50/200 yard zero works.
Great Information, Thanks.
lifebreath
04-06-11, 14:44
Great info - thank you!
Traveshamockery
05-01-11, 07:39
Great thread. Thanks from a relative AR newb.
There are apparently a lot of graphics (especially on the first page) that I am not getting (lots of white space). I am using Firefox 4. Can I fix this or are they gone?:confused:
There are apparently a lot of graphics (especially on the first page) that I am not getting (lots of white space). I am using Firefox 4. Can I fix this or are they gone?:confused:
Repeating my earlier post:
Are you running Zone Alarm or any other Browser Security Program? I checked Zone Alarm is blocking www.box.net as it is a known site for distributing spyware.
Repeating my earlier post:
Are you running Zone Alarm or any other Browser Security Program? I checked Zone Alarm is blocking www.box.net as it is a known site for distributing spyware.
Yes, I'm running Zone Alarm and don't intend to shut it off.
I did change my internet zone to medium for a minute and it didn't make any difference.
Turned ZA off for a minute and used IE8. Got the little boxes with a red X.
Added www.box.net to the trusted sites list. No change. Maybe I need to restart or something?
Yes, I'm running Zone Alarm and don't intend to shut it off.
I did change my internet zone to medium for a minute and it didn't make any difference.
Turned ZA off for a minute and used IE8. Got the little boxes with a red X.
Added www.box.net to the trusted sites list. No change. Maybe I need to restart or something?
Click on this link to one of the pictures: http://www.box.net/shared/static/l5orbycc2z.jpg
You will get a warning from ZA, select the stay on site and you will see the picture. You can then go back to the first page and all of the pictures will now be seen.
Click on this link to one of the pictures: http://www.box.net/shared/static/l5orbycc2z.jpg
You will get a warning from ZA, select the stay on site and you will see the picture. You can then go back to the first page and all of the pictures will now be seen.
I get a "Connection Was Reset" message.
I get a "Connection Was Reset" message.
Do you see the Zone Alarm button on the toolbar just below the URL? Click it and and select settings. Uncheck the block spyware sites. You will want to turn it back on later.
Do you see the Zone Alarm button on the toolbar just below the URL? Click it and and select settings. Uncheck the block spyware sites. You will want to turn it back on later.
I have the free version. No button for spyware. I am running Avast too, but can't find anything about spyware in it. I have an HP computer. Could HP have something that affects it?
I have the free version. No button for spyware. I am running Avast too, but can't find anything about spyware in it. I have an HP computer. Could HP have something that affects it?
Ok, Avest it probably blocking the site. I am not familiar with it so all i can suggest is go to their forums and ask there.
Ok, Avest it probably blocking the site. I am not familiar with it so all i can suggest is go to their forums and ask there.
Thanks for all your effort. I have an older computer that caught a BAD bug.. When I get around to reformatting it and reinstalling the OS, I'll try it without any extras and see what happens. If I catch something on it I'll just do it again.
offroader1006
05-25-11, 15:59
oops, posted in wrong thread.
cochraneap
06-02-11, 10:29
very informative. thank you!
This is insane! Thanks for the good work Molon, I can't begin to imagine the effort required to put this information required.
Its much appreciated.
Very good information. I've got a plain vanilla A2 HBAR (20 inch barrel) that I've yet to take to the range. I intend to zero it at 100 yards. From reading this, a 100 yard zero is probably not practical with the "as is" A2 sights. Correct?
Very good information. I've got a plain vanilla A2 HBAR (20 inch barrel) that I've yet to take to the range. I intend to zero it at 100 yards. From reading this, a 100 yard zero is probably not practical with the "as is" A2 sights. Correct?
Not sure why you say this. It should be very doable. Why do you think it isn't?
Is it the "practicality" aspect of a 100 yd zero that you're commenting about? That was the whole reason behind the IBZ which covers muzzle-just over 200 yards with only a couple of inches high or low. Going against a target sized like a human's torso, that's a pretty "practical" zero.
But if you want to zero for 100 yards, it's entirely doable. Just note that when you get out to 200, 300, you'll be way low. That's why you have the elevation wheel in the rear sight, to bring the trajectory back up.
NM High Power shooters shoot reduced course matches all the time at 100. They also shoot various stages at 200, 300 and 600 when shooting XTC. They have their books and they document how many clicks up the move the rear site. It's all load/BC/velocity dependent, what works for one guy using one bullet type/weight won't necessarily translate to a different load, but it should be close enough that you can tweak the come ups for longer distances for your rig. Or you can use a software program like Molon does in his illustrations. Again, that will get you close, but you'll have to shoot your particular rig to fine tune it.
Maybe I'm reading too much into the text (or missing the obvious) but this is from the primer on Revised Battlesight Zero at the beginning of this section:
"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, 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."
Maybe I was kind of vague. The "out of the box" A2 would need the attention of an Allen wrench to achieve acceptable zero at 100 yards, if I'm reading this correctly.
I should probably add that this is just for seeing how accurately I can punch paper at the range, not for combat/HD purposes. My formal instruction was in the Air Force using the old A1 sighting system, so the A2 is a new experience for me.
Like I say, HP shooters shoot reduced course matches all the time at 100. They're zeroing somehow.
Not sure if they if they bottom out the wheel and adjust front accordingly, or if like Santos, they make the allen screw adjustment to the wheel. Once the rear is set for the zeroing distance, all elevation adjustments are made to the front site.
The rule is, adjust front site opposite the direction you want bullet impact to move. If for some reason you end up raising front post as much as you think you can (it's wobbly, you see light under the base) and your impacts are still high on the target you can swap out the front post for a taller one from Bushmaster. They're around $5. Or you make further adjustments to the rear elevation wheel and lower it some more.
If you're really serious and want to know how to set the wheel for further distances, then plot how much off you are at the further distances as you move the wheel to the 3, 4, 5 and 6 settings for the distances you are shooting at. I think std rear elevation adjustments are .5 MOA/click, but I'm not positive on that. Just remember these are in MOA and you have to do the math to get your desired POI for each distance. For example, assuming .5 MOA per click, one click at 600 yards would move POI ~ 3 inches. The same one click adjustment at a 300 yard target would shift POI ~ 1.5 inches. And, when you change loads, you get to do it all over again. Fun, fun, fun.
My unsolicited advice: Pick one commercial load or develop one good load and stick with it. Then get a chronograph. Knowing your muzzle velocity, you can figure out a lot of things, even the actual BC of your load through your barrel which can differ from what the ammo/bullet mfg publishes. Knowing starting velocity and BC, you can then use the available software tools to determine MOA drops across the distances you'd be shooting, and knowing that you can derive "come ups" on your elevation wheel as you shoot targets at varying distances. You'll also need to be a good judge of distance or know the distance from the range. If out in the open a laser range finder can be very helpful.
Or you can blow all this off, guesstimate the distance, and just have some fun. It just depends how serious you are about long range shooting with irons.
I appreciate the tips. I'm just a recreational shooter (like probably 99%of the peope that buy an AR), so any advice is welcome.
I took a bit of ribbing from friends when buying a rifle instead of a carbine-length weapon ("Dude, no one buys those things any more" and "This ain't 1975, guy"). But, as a fun gun/plinker I think it'll do fine :D
Great thread very helpful information. I get to know about the trajectory of a gun.
ONEmanWOLFpack
06-12-11, 08:38
Very informative! Great for a new owner like myself..
Incredibly helpful post! Great info.
BearClaw Bigsby
07-10-11, 13:31
invaluable information for a novice shooter
I have been using the 50/200 yard zero with success. I chronograph my ammunition and run the velocity on Rem Shoot software before zeroing the rifle. I zero the rifle at 50 yards then confirm the point of impact at 100 yards, 150 yards, 200 yards and 300 yards. I sometimes have to make small adjustments at longer ranges, which results in a very small change in point of impact at 50 yards. I usually have to add 3 MOA elevation to zero at 300 yards with this method.
Invaluable information. All to common do you find a post or thread "do it this way because I said so and the reason doesn't matter". This thread, especially the OP provides a solid detailed explanation of how and why to use these methods and goes further by explaining the mechanics to the formula for this sighting procedure.
Very well done and benefits novice as well as seasoned shooters.
This has been very helpful.
blairellis
08-22-11, 08:47
Thanks for the informative post. Great info here!
Great post, do you have any information for a 55 grain round out of a 16" barrel? Most law enforcement agencies use 55 grain rounds out of a 16" barrel.
RogerinTPA
08-25-11, 19:47
Great post, do you have any information for a 55 grain round out of a 16" barrel? Most law enforcement agencies use 55 grain rounds out of a 16" barrel.
Re-read this thread from page 1 on. Most, if not all of the graphs, represent both 55gr M193 and 62 gr M855 ammo trajectories.
Thank you for this excellent post.
I have been told to zero at 25 yards by a retired Army designated marksman trainer at the gun store.
I currently zero the Daniel Defense M4 at 50 yards. This seems to be a good spot for LE purposes. Center mass with the aimpoint and the impact is within a reasonable circle. Perhaps this is not precise enough for sniper use but it seems like a good setup for "active shooter" scenarios.
Have you attempted to shoot at farther distances (150yds+)once you zeroed at that distance to see if you will hit center of mass??
The rifle is fairly new and has only been fired out to 100 yards. I will test it out at 200 and further in the coming weeks.
let me know the results. I am not looking for sniper quality, just center of mass hits
billybob19606
08-31-11, 23:03
Hi everyone,
I read Molon's posts on the trajectories in this thread. He seems to have lots of good insight on this subject, and since I'm a newbie, I thought Id ask.....
I just bought my first AR..it's a DanielDefense M4 with a 16" barrel. I got a good deal on PMC 5.56 x-tac ammo (62grains), so that's what i've been shooting.
My question to you is: Are these following results ok/normal? (i used iron sights)
At 50 yards, after 10 shots I was consistently grouped about 3/4" inch low. I left my sights alone and then took 10 shots at 100yds. I was about 3" high at 100yd. I went to 200yds and had a 7" group all around the center. They didnt seem to be too high, nor too low.
If I'm a little low at 50, is it w/in reason to be 3" high at 100yd, then back to zero at 200?
I keep looking at the charts/graphs and breaking this stuff down. Im guessing my PMC 62 grain ammo preforms closer to the 855, than it does the 193 round.
Thank you very much for any insight anyone could provide,
~Billy
.
BB,
Congrats on the fine rifle.
50 yards is an "about" near zero for most guns and most 50g to 62g ammo.
Sounds like you did things correctly, which is shoot at the near zero and then verify at the far zero.
But maybe it's just me...
.
jtsikes0204
09-04-11, 05:10
wow......great thread.
The first time I went thru this thread I couldn't get most of the graphics to display (I use Firefox). Tried and tried with no success. It was still a great thread with more useful info than anything else I have seen.
I just tried it with IE 8 and the graphics DO show up. Upgrade rating to an amazing thread.
On a side note; I have ready access to a 100yd range, 200 is much harder to get to. From the trajectory charts, it looks like I will be doing a 50 yard zero and verifying 1.5 to 1.6 inches high at 100 yards. That should put me pretty close at 225yd right.
billybob19606
09-11-11, 19:27
Thanks for all the help. I bought an Eotech and it and the irons all line up great. 50yd and 200yd is a great way to zero, Thanks again
I use RIBZ on a stock, plain Jane CMMG mid-length AR. After a 50 zero, I took the rifle to the 200 yard range and without making any adjustments of any kind and on a 82 degree F day, I shot at my target, results were about .75 MOA group above the X ring.
Hi everyone,
I read Molon's posts on the trajectories in this thread. He seems to have lots of good insight on this subject, and since I'm a newbie, I thought Id ask.....
I just bought my first AR..it's a DanielDefense M4 with a 16" barrel. I got a good deal on PMC 5.56 x-tac ammo (62grains), so that's what i've been shooting.
My question to you is: Are these following results ok/normal? (i used iron sights)
At 50 yards, after 10 shots I was consistently grouped about 3/4" inch low. I left my sights alone and then took 10 shots at 100yds. I was about 3" high at 100yd. I went to 200yds and had a 7" group all around the center. They didnt seem to be too high, nor too low.
If I'm a little low at 50, is it w/in reason to be 3" high at 100yd, then back to zero at 200?
I keep looking at the charts/graphs and breaking this stuff down. Im guessing my PMC 62 grain ammo preforms closer to the 855, than it does the 193 round.
Thank you very much for any insight anyone could provide,
~Billy
Different grain bullets and loads will give us slightly different results and trajectories. However we can all agree that zeroing at 50 yards gives us the flattest and most practical trajectory for the 5.56mm/.223 Rem.
billybob19606
10-25-11, 23:50
I did the same 50yd zero as I did w/ my 16" DD, and at 100yd it was still grouping about 2" high, but when I went back to 200yd, the group was pretty consistent at about 4" low (where my 16"DD was only about an inch or less low)
Does a 14.5 barrel slow the bullet velocity down, and would a muzzlebrake slow it even more?
The groups were pretty tight, but just a lil lower @200yd than I had anticipated.
Thanks for any feedback/insight! :)
I did the same 50yd zero as I did w/ my 16" DD, and at 100yd it was still grouping about 2" high, but when I went back to 200yd, the group was pretty consistent at about 4" low (where my 16"DD was only about an inch or less low)
Does a 14.5 barrel slow the bullet velocity down, and would a muzzlebrake slow it even more?
The groups were pretty tight, but just a lil lower @200yd than I had anticipated.
Thanks for any feedback/insight! :)
what ammo? it sounds like something weak like PMC? was it heavier than 55grain?
billybob19606
10-26-11, 15:57
Yes, and yes! LOL
PMC 62grain. However, it was the same ammo that I was using in my DD 16" that was about 2" high (at 100yd) and zero'd at 200yd
Great Thread Molon I will be going out and sighting in my AR again after I paint it this winter. Again thanks for the great info.
I have a Colt 6920, 1:7 twist 16in. detachable carry handle, firing xm193, and I followed the IBZ instructions and was able to group very well at 100 yards using -6 clicks, and I also grouped very well at 50 yards, -4 clicks using the small, unmarked aperture. My question is if I return the rear setting to 6/3 and use the 0-2 large aperture will my rifle shoot POA/POI inside 0-200 yards? Thank you in advance for any responses.
In Houston were are recommending the 50 yard zero.
In Houston were are recommending the 50 yard zero.
===============================
Just curious, what does "Houston" have to do with the zero and who is "we" (or were)?
.
RogerinTPA
01-14-12, 07:29
In Houston were are recommending the 50 yard zero.
Who's we?
viperashes
01-14-12, 07:47
I have a Colt 6920, 1:7 twist 16in. detachable carry handle, firing xm193, and I followed the IBZ instructions and was able to group very well at 100 yards using -6 clicks, and I also grouped very well at 50 yards, -4 clicks using the small, unmarked aperture. My question is if I return the rear setting to 6/3 and use the 0-2 large aperture will my rifle shoot POA/POI inside 0-200 yards? Thank you in advance for any responses.
What the 0-2 sight is for is fighting inside of 200 yards. It's not supposed to be a precision shooting aperture. Short answer, no. Long answer, Yes, if you were capable of lining the front sight post up dead center of that aperture consistently, and hold it there, you would theoretically shoot POA/POI or very close to it. I have yet to meet anyone who can do it consistently.
For precision aimed shots, use the small aperture, even inside of 200. For quick target aquisition using iron sights, use the 0-2 sight, but don't adjust your elevation to use it, because it really serves you no purpose. Just put the tip of the front sight post relatively in the middle of the aperture, and pull the trigger. It's basically a bullet hose sight, as it realistically would only be good for suppressing fire on an area.
Molon,
like the above poster,
I am using a RDS. I do not get anything like the 50/200 IBZ. Granted, I am using a 10.5" SBR w/ 69gr handloads. However, I zero at 50yds, and even at 100 yards, I am seeing an approx 3-4" drop. At 200yds, I was about 6" low. Does the IBZ not apply to a RDS since one is not looking thru the rear aperature to the front?
TIA, and thanks for all your helpfuls posts. Truly appreciated.
Yes, I would like to hear from people running 70-75 grain ammo out of shorte barrels as well. I am running 70gr tsx and 75gr otm's out of a 14.5" using an aimpoint, and when I zero at 50 I am a good 2" high at 100. 100 yards is all I I currently have access to. So how is the hevier stuff doing out past 200 with a 50 yard zero?
TacMedic556
03-15-12, 09:48
A great explanation of the M4 zero:
http://www.youtube.com/watch?v=TgyRBqcsRcE
Failure2Stop
03-15-12, 10:09
A great explanation of the M4 zero:
http://www.youtube.com/watch?v=TgyRBqcsRcE
There is much better info in a single thread here than in that video.
Nothing against Rich, just sayin'.
TacMedic556
03-15-12, 20:39
Oh I know man. This thread is top notch! Some guys just need the simple part explained with crayons and a white board. I have had to explain the fact that bullets do not generate "lift" and flight like the foil on wings to too many buddies. Figured some guys would "get it" with the explanation.
machinegunbob
03-21-12, 09:26
I found that the US Army sighting targets will get the job done fairly good.
A great thread with well stated information. Thanks for efforts.
One quiet range day, this discussion came up.
Our patrol rifles are zeroed at 50 yards. The training
includes firing at 7 yards to demonstrate the height over bore relationship between POA/POI. The theory being that a threat at relatively short range is exposing only a small portion of their head and the POA would have to be at the top of his head to strike between the eyes.
Assuming this theory is valid, if the height over bore is 2 Ľ inches, and we zeroed the sights so POI was 2 Ľ below POA at a distance of 5 yards (or whatever), would the results be a 50 yard zero.
We tried it just for kicks and it appears to provide a reasonable zero. Adjustments are very critical.
Again, thanks for the invaluable information, well illustrated.
Assuming this theory is valid, if the height over bore is 2 Ľ inches, and we zeroed the sights so POI was 2 Ľ below POA at a distance of 5 yards (or whatever), would the results be a 50 yard zero.
We tried it just for kicks and it appears to provide a reasonable zero. Adjustments are very critical.
I believe the sights on an M4 are about 2.6" above the bore axis...
Just a big "thanks" for this thread -- Got more usable info and more understanding on what's going on 'in the air' from the first page of this thread than the sum total of everything everyone has tried to explain to me.
Looking forward to sighting things in with a a little more confidence.
madmike3668
04-24-12, 02:43
Yes thanks a lot guys! This thread is very helpful to a newbie like myself. Gives me a much better understanding of bullet trajectories. Thanks for the information.
Super_Ninja
05-13-12, 10:13
I'm getting ready to change to a 11.5" upper for work. I use the 50 yard battlezero on my 16" now. Is the 50 yard zero as flat & useful on the 11.5" as it was on my 16" barrel? Duty ammo is Hornady TAP 55gr and both barrels have a 1:7 twist. Thanks for any/all help.
Stay safe.
viperashes
06-04-12, 00:13
I'm getting ready to change to a 11.5" upper for work. I use the 50 yard battlezero on my 16" now. Is the 50 yard zero as flat & useful on the 11.5" as it was on my 16" barrel? Duty ammo is Hornady TAP 55gr and both barrels have a 1:7 twist. Thanks for any/all help.
Stay safe.
A 50 yard zero is basically going to be the same between the two. For LEO work, you're almost better off with a 100 yard zero. It's a flatter trajectory and holds are simpler. That and your zero basically means that 300 yards is about your maximum range before you get severe bullet drop. For LEO work, if you're shooting your patrol rifle farther than that, you dun goofed.
ParanoidCivilian
07-18-12, 22:18
The instructions say they are for 8/3, mine are 6/3? What should I do?
if you are using a 11.5 inch barrel, I would recommend sighting in at 25 yards. 11.5 are for CQB and have no practicle use past 200. 200 is really pushing it for an 11.5. Our motor units carry 11.5 on the bikes and we sight them in at 25yd. 11.5 lose a lot of velocity regardless of what ammo you are using. You have to pick the right rifle for the job. If you are in an urban environment, look across the street and depending on where you live, that could be between 25-50 yards. I would never use a 11.5 unless it was an entry. I would stick to 14.5 or 16 for urban. :big_boss:
Failure2Stop
07-23-12, 00:57
if you are using a 11.5 inch barrel, I would recommend sighting in at 25 yards. 11.5 are for CQB and have no practicle use past 200. 200 is really pushing it for an 11.5. Our motor units carry 11.5 on the bikes and we sight them in at 25yd. 11.5 lose a lot of velocity regardless of what ammo you are using. You have to pick the right rifle for the job. If you are in an urban environment, look across the street and depending on where you live, that could be between 25-50 yards. I would never use a 11.5 unless it was an entry. I would stick to 14.5 or 16 for urban. :big_boss:
A 25 meter zero actually makes 0 to 200 meter engagements (specifically the 0 to 25) more difficult than the other zeroing methods (50/200 or 100 meter POA/POI zeroes). Take a look at the trajectory charts in this thread and take a look at the linked thread for more information:
https://www.m4carbine.net/showthread.php?t=107572
The instructions say they are for 8/3, mine are 6/3? What should I do?
For 6/3 marked sights you will need to be able to fully reach 6/3(- 4).
That is 4 full clicks "below" 6/3. Lots of folks will have their sights set so that they can go to (-5), but set it on (-4) to ensure that they have the detent fully rested.
The reason is that the 6/3 marked sights have half of the adjustment as the 8/3 marked sights per click, therefore you need to use twice as many clicks to travel the same distance.
if you are using a 11.5 inch barrel, I would recommend sighting in at 25 yards. 11.5 are for CQB and have no practicle use past 200. 200 is really pushing it for an 11.5. Our motor units carry 11.5 on the bikes and we sight them in at 25yd. 11.5 lose a lot of velocity regardless of what ammo you are using. You have to pick the right rifle for the job. If you are in an urban environment, look across the street and depending on where you live, that could be between 25-50 yards. I would never use a 11.5 unless it was an entry. I would stick to 14.5 or 16 for urban. :big_boss:
Dear God. That just sounds like a whole truckload of bad advice and bad information, largely gleaned from folklore, out of date theory, and Internet reading.
What happens when one of those motor cops arrives at a parking lot and starts winging shots out across the open prairie at some similarly-armed bad guy?
With modern ammunition choices the maximum effective range of the 5.56, even out of shorter barrels, is greatly increased, and even if it isn't a hit is still better than a miss.
There is no reason for a 25 yard zero that good training can't overcome.
GUNSLINGER67
07-26-12, 08:04
Excellent info Molon , thank you .:cool:
bronson224
08-06-12, 12:08
Okay, so this is my first time on the forum and my first post. From reading through this a little bit it looks like for a 50yard zero i want to be about an inch low at 30yd right? the reason I ask is cause i just got a new AR and i want to sight it in for 50Yds but my local range only has a 100yd and 30yd rifke range and they wont let you place targets at any other distances. Ive never shot the rifle let alone with my optic on it so i have no idea where its going to be hitting at any distance yet. Thanks for any help and sorry if this isnt the right places for the question.
Cincinnatus
08-06-12, 12:16
Nevermind. As you were.
Failure2Stop
08-06-12, 12:36
Highly recommend just going point of aim/point of impact at 100.
Sent from my DROID RAZR using Tapatalk 2
Highly recommend just going point of aim/point of impact at 100.
Why? So that you're low at every range but 100 yards?
Pardon my ignorance, but looking at the ballistics charts tells me that if you zero for 100 yards/meters, that's it...you're at the top of the parabolic arc.
When you zero for 25/300 or 50/200 (your choice), you're high between these distances, but not by more than 8"-10" (with a 25 zero) or 4"-5" (with a 50 yd zero)...
Am I missing something?
Edit: Maybe I am...Reading your "Zen of 100m Zero" now...Maybe I'll learn something! :-)
Cincinnatus
08-06-12, 14:50
Why? So that you're low at every range but 100 yards?
Pardon my ignorance, but looking at the ballistics charts tells me that if you zero for 100 yards/meters, that's it...you're at the top of the parabolic arc.
When you zero for 25/300 or 50/200 (your choice), you're high between these distances, but not by more than 8"-10" (with a 25 zero) or 4"-5" (with a 50 yd zero)...
Am I missing something?
Edit: Maybe I am...Reading your "Zen of 100m Zero" now...Maybe I'll learn something! :-)
The arc is not a rainbow. It's a difference of within six inches or so, depending on what distance one is shooting. Well within the accuracy requirements for minute-of-badguy in a defensive carbine--Unless one seriously thinks you're going to be using your rifle to take out a hostage-holding terrorist at 400m. :))
Looking over Failure2Stop's Zen of the 100 Meter Zero (http://m4carbine.net/showthread.php?t=107572), I must admit it makes a lot of sense. I'll have to give it a try.
~Dan
Thanks Molon alot of great info in one thread so I don't have to search for it on the web.
KarbonChemist
10-05-12, 12:18
This is a FANTASTIC thread. Tons of useful info.
initialkev
11-01-12, 05:53
If you put the barrel parallel to the ground and the bore axis perfectly centered on the bulls eye at a 100 yards, how much will a 55gr bullet drop?
Failure2Stop
11-01-12, 07:01
If you put the barrel parallel to the ground and the bore axis perfectly centered on the bulls eye at a 100 yards, how much will a 55gr bullet drop?
http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi
Doc. Holiday
11-06-12, 15:02
There are a bunch of ballistic calculators out that that can help you figure that out including Apps for your phone.
Thanks Molon. I have been running a 200 yard zero on my AR-15s for about 30 years with good results. About 10 years ago I read an internet post by a US Marine Corps officer, his name was Sanchez I think, and learned to reset the rear sight elevation knob like you showed on your post. I can shoot neck hold at 300 yards or come up 3 minutes to the 300 yard setting and shoot POA with good resuits.
I am going to check out Failure2Stop's Zen of the 100 Meter Zero and give that a try. Sometimes you can teach an old dog new tricks.
I k ow tho thread is as old as can be, so ill just ask an hope the best. I'm hoping for the 100 yrd and my Matech BUIS lowest setting is 200. Are these instructions on how to adjust the rear sight applicable for the MaTech BUIS as well or is there another scheme I should apply to get this particular rear sight set to zero at 100. I like the 100 yard due to my only concern should be hold over (and not under). Well, her's me wishing for a reply on a older than dirt thread. I'm just hoping enough people (like me) are referred to this thread tht I might find one person who an lens their guidance
Inkslinger
01-01-13, 15:38
If you adjust your front sight till POA/POI is on at 100, that will mean the 200 on your sight is now 100. Viola!
Failure2Stop
01-01-13, 15:42
I k ow tho thread is as old as can be, so ill just ask an hope the best. I'm hoping for the 100 yrd and my Matech BUIS lowest setting is 200. Are these instructions on how to adjust the rear sight applicable for the MaTech BUIS as well or is there another scheme I should apply to get this particular rear sight set to zero at 100. I like the 100 yard due to my only concern should be hold over (and not under). Well, her's me wishing for a reply on a older than dirt thread. I'm just hoping enough people (like me) are referred to this thread tht I might find one person who an lens their guidance
Due to front sight obscuration of small targets at distances past 100 meters, I recommend zeroing iron sights for 200 meters, unless the irons are going to be an infrequently used secondary sighting system for an optic. If it is a back up, I recommend having it set with the same zero as the primary, unless you are going to spend significant time on the irons to ingrain the different trajectory. If the irons are stand-alone I recommend zeroing them to maximize their built-in utility, which in this case would be a 200 meter zero.
Typos brought to you via Tapatalk and autocorrect.
Due to front sight obscuration of small targets at distances past 100 meters, I recommend zeroing iron sights for 200 meters, unless the irons are going to be an infrequently used secondary sighting system for an optic. If it is a back up, I recommend having it set with the same zero as the primary, unless you are going to spend significant time on the irons to ingrain the different trajectory. If the irons are stand-alone I recommend zeroing them to maximize their built-in utility, which in this case would be a 200 meter zero.
Typos brought to you via Tapatalk and autocorrect.
I agree with you 100%. I believe the 200 meter or 200 yard zero is a good all round zero. The bullet path does not leave the sight plane more than 2" from 8 yards to roughly 220 yards. With the 200 meter/yard zero, you can aim neck hold at 300 and get good COM hits. I zero the M1A in the same manner and have had good luck with it over the past 30+ years.
LMT Shooter
01-03-13, 21:36
Our departments range only goes out to 50yds, so I have been using this thread to show our officers that they are not at any sort of disadvantage (and actually, I think, at a distinct advantage) by zeroing at 50yds, which is a pretty common perception. This thread is probably one of the most useful ones on the forum.
Our departments range only goes out to 50yds, so I have been using this thread to show our officers that they are not at any sort of disadvantage (and actually, I think, at a distinct advantage) by zeroing at 50yds, which is a pretty common perception. This thread is probably one of the most useful ones on the forum.
Having a 50 yard range can limit you to what you can do, but you can still get a decent zero at that range. I had a 25 yard range at the district and had my officers shoot for POI at -1" at 25 yards. This is close to the 50/200 yard zero. I made friends with people at two of our local gun clubs, so we could use their facilities to qualify at 100 yards. Most of our people did not have to make any sight adjustment at 100 yards and those that did were only required to move the rear sight elevation/windage knobs 1 or 2 clicks at most.
Try contacting local gun clubs and ask about using their ranges to shoot longer distances. I have found that my local gun clubs are very supportive of law enforcement and military personnel.
I agree with you about this forum. There is a lot of good information available.
ZuluCharlie
02-07-13, 19:52
Very helpful and informative.
leeradio13
02-18-13, 22:17
amazing, does this help in the pressures of battle?
Failure2Stop
02-18-13, 22:25
amazing, does this help in the pressures of battle?
A well thought out zero certainly helps in a gunfight by simplifying decisions in certain envelopes of application.
Typos brought to you via Tapatalk and autocorrect.
guitarman008
02-21-13, 21:03
Very helpful! Thank you for making it so clear to a noob. I can't wait to try your zeroing suggestions Molon. Just need some more ammo :)
amazing, does this help in the pressures of battle?
Yes it does.
Since the 50/200 thing is generally true, (where a rifle zeroed at 50 is more or less on at two hundred yards),
Will my rifle that is exactly dialed in at 200m also be on at 50m?
I know this sounds like a dumb question, but I'd rather ask than not at all.
Failure2Stop
03-04-13, 14:05
Since the 50/200 thing is generally true, (where a rifle zeroed at 50 is more or less on at two hundred yards),
Will my rifle that is exactly dialed in at 200m also be on at 50m?
I know this sounds like a dumb question, but I'd rather ask than not at all.
Yes, and that's a better way to think about the zero.
Yes, and that's a better way to think about the zero.
Good. I have a fixed rear sight and the front post is set for 200m. I don't want to move it around for shorter distances, so I thought I'd ask.
This was some great information.
Does anyone have ballistic information for the M855 and M193 (or similar rounds) shot out of a 10.5" to 11.5" barrel? I could not find it in the forum.
Thanks,
jemoritz
saddlerocker
05-02-13, 17:39
Are there any trajectory charts for 7.62x51/308 from 16-20" barrels?
Sorry if I messed them.
I set my ACOG to 100meter zero, but I have been trying to figure out where to zero my iron sights and RMR.
on my SBR I use the 25 meter to get on paper then push it out to 100yds..
;)
http://www.box.net/shared/static/dzt2hes8h8.jpg
I would like to know where to buy this book.
I would like to know where to buy this book.
I believe the OP supplied the initial draft in page 1 of this thread.
:D
Has anyone else tried the 255m Zero? I have been using this with my platoon for the last two years or so it has worked great. It's supposed to be +/- 4" from your line of sight out to 300m. I haven't tried it on paper but as soon as I do I'll post pics.
(I think it's 4" trying to remember I'll post the publication on Tuesday when I get to the office)
Edit 8-23-14
Having trouble posting the pic (fix later) but here are the numbers:
Meters. Trajectory " off LOS
0. -2.5
150. +4.45
300. -4.86
With an M4 and NATO green tip ammo
With a 200m zero you are -10" at 300 and with a 300 zero you are +7". The 255 has worked really well.
With a 20" barrel max LOS difference is 3.8"
Anyone else use it?
Just wondering if I am doing this right with my Matech BUIS and DD fixed front sight. I zero at 50 yards with M855, so I set my Matech to 200 right?
Also, when I did zero the gun, I noticed that the front sight post was sitting a little lower than I am used to seeing on normal FSB's.
How would one find a near zero for there rifle before trying to site it in if they want a 200 yard far zero? Is it possible to do a 30 yard near zero or something similar?
How would one find a near zero for there rifle before trying to site it in if they want a 200 yard far zero? Is it possible to do a 30 yard near zero or something similar?
Adjust your iron sights to hit 1" low at 25 yards with a 16" barrel. That will get you on paper at 100 yards where you want to hit roughly 1-1/2" high. That will get you close to zero at 200 yards with most ammunition.
Doc. Holiday
08-26-13, 18:02
If you zero your rifle for 50 yards, it will be zeroed at 200 yards. They both share the same zero.
I am confused it doesn't seem to me that all 223 bullets would share the same trajectory. Is there a program or something to use to help with the calculations? Would it work the same with a scope?
Bullet weight, muzzle velocity and ballistic coefficient are the key factors. The trajectory of a 55g 5.56mm and a 55g .223 cartridge loaded with a similiar projectile at the same velocity should be close to the same.
Optics should not have an effect on trajectory out to 400 yards if the center of the optic is the same height over the bore axis as the iron sights you are using. The M4/M16 platform with fixed front sight base has a sight plane that is 2.6" over the bore axis. Hitting 1" low at 25 yards for a rough 200 yard zero is based on that measurement.
The Godevil
08-26-13, 21:25
http://www.jbmballistics.com/cgi-bin/jbmtraj_simp-5.1.cgi
I am confused it doesn't seem to me that all 223 bullets would share the same trajectory. Is there a program or something to use to help with the calculations? Would it work the same with a scope?
http://www.glocktalk.com/forums/showthread.php?t=1501497
I wasn't able to post pics on here so ill post a link
How would one find a near zero for there rifle before trying to site it in if they want a 200 yard far zero? Is it possible to do a 30 yard near zero or something similar?
You got one good answer; also there are ballistics calculators and some tables out there that list results for different ammo. Best data though is what you get with your own rifle/ammo.
I figured outt this weekend that shooting ammo that groups well in your rifle then shooting at different distances is the best way to figure out how you gun is shooting at different distances. Plus it is fun practice.
How would one find a near zero for there rifle before trying to site it in if they want a 200 yard far zero? Is it possible to do a 30 yard near zero or something similar?
I usually start at 25 yards to rough zero a rifle, then shoot at 50, 100, 200 and 300 yards to verify my zero. Your question prompted me to throw a couple of extra rifles in the Jeep yesterday, so I could check my points of impact at 30 yards for myself. My rifle and carbine are both zeroed at 200 yards with M193, which was verified before firing at 30 yards. I rezeroed with M855 before firing at 30 yards. All groups fired with iron sights from the prone position at 200 yards ran from 3-1/2" to 6" center to center. Note: I don't carry a concrete bench around with me, so I always zero from the prone position.
Conditions-sunny, 80 degrees, winds 190 degrees relative at 5-10 mph. All shots were fired between 10:00 A.M. and 12:00 P.M.
AR-15 rifle with 20" barrel:
M855 ball velocity measured 3017 fps at 15 feet from the muzzle
M193 ball velocity measured 3238 fps at 15 feet from the muzzle
AR-15 carbine with 16" barrel
M855 ball velocity measured 2946 fps at 15 feet from the muzzle
M193 ball velocity measured 3065 fps at 15 feet from the muzzle
The center of the SR-21 target repair center was placed 15" above the ground and 10 shot groups were fired from the prone position. The barrels were fouled. The groups at 30 yards were 1" with M193 and 3/4" with M855. POI was measured from the POA to the center of the shot group.
Rifle POI:
M855 POI - -1-1/4" at 30 yards
M193 POI - - 1" at 30 yards
Carbine POI:
M855 POI - 3/4" at 30 yards
M193 POI - 1" at 30 yards
And before the question is asked the answer is no, I did not take a camera to the range.
If you are going to zero at 30 yards and are firing the same ammunition, this should give you a starting point.
thopkins22
09-13-13, 13:43
Keep in mind that the closer you shoot your zero, the more you're going to be off at your intended zero. Conversely, if you can't hold a good group at 200, there's no point to attempting it. Personally I like to zero 1"-1.5" high at 100, and then shoot the rest of my yardages and walk the ground and see what's actually happening.
With that said, I have a target designed to put you on a fifty yard zero by shooting at 25 yards, if you like I'll email it to you. I just don't really recommend it unless you absolutely positively don't have access to a real rifle range.
At 25 yards your POI should be roughly an 1.1" lower than your POA.
As T2C is inferring, all of this 50/200 is VERY dependent on load and rifle combination. But it'll be close enough that the differences likely won't matter too much...but you truly will not know until you actually shoot it, walk the ground, and see what happens.
noliver,
I suggest logging your observations and shooting results for each trip to the range. If for no other reason, you will know what sight adjustments to make if you are zeroed for M855 and all you can find on short notice for a three gun match is Wolf 55g.
Gray Ghost
11-20-13, 14:32
I bought a KAC 300 meter BUIS for my 10.3" AR-15.
I want to zero it for 300 meters with 62gr M855 ammo on a 100 yard rifle range.
How high should my rounds be hitting on the target at 100 yards?
Thanks
I bought a KAC 300 meter BUIS for my 10.3" AR-15.
I want to zero it for 300 meters with 62gr M855 ammo on a 100 yard rifle range.
How high should my rounds be hitting on the target at 100 yards?
Thanks
My rifles seem about 2-4 inches off at 100, depending on ammo; best to just zero at 25meters and adjust from there, as the 25/300 is the current "battle sight" distance. Then, once zero'd at 25m, you can see about where you'll be at 100 yards.
Gray Ghost
11-20-13, 15:45
My rifles seem about 2-4 inches off at 100, depending on ammo; best to just zero at 25meters and adjust from there, as the 25/300 is the current "battle sight" distance. Then, once zero'd at 25m, you can see about where you'll be at 100 yards.
I don't have access to a range that measures anything in meters. They may have a 20 yard line for pistols but I'm not sure.
More than likely for rifles, they've just got the range marked at 50 and 100 yards.
I don't have access to a range that measures anything in meters. They may have a 20 yard line for pistols but I'm not sure.
More than likely for rifles, they've just got the range marked at 50 and 100 yards.
A 50 yard zero is roughly a 200 yard zero. Point of Impact at 100 yards will run from 1-1/4" to 2" high depending on ammunition and barrel length.
Failure2Stop
11-22-13, 06:27
I bought a KAC 300 meter BUIS for my 10.3" AR-15.
I want to zero it for 300 meters with 62gr M855 ammo on a 100 yard rifle range.
How high should my rounds be hitting on the target at 100 yards?
Thanks
The 300 meter BUIS doesn't have to be zeroed at 300 meters, and doing so is going to severely limit your applicable envelope with that barrel length.
However, if that's really what you want, the POI will need to be about 5"-6" high at 100 with a 10.3 barrel and M855.
Gray Ghost
11-22-13, 19:55
The 300 meter BUIS doesn't have to be zeroed at 300 meters, and doing so is going to severely limit your applicable envelope with that barrel length.
However, if that's really what you want, the POI will need to be about 5"-6" high at 100 with a 10.3 barrel and M855.
Thank you for answering my question.
Since this thread is sticky, I'll necro to mention that this post is top shelf. Thanks so much for the effort.
The Annoyed Man
04-19-14, 10:48
Not to necro again, but I've bookmarked this thread for the information on the Santoze modified 50yard/200meter zero. I do have a question for Molon if he cares to answer it:
Preface:
I have a Trijicon TA31F (4x32, red chevron) for my primary carbine optic, and I am not certain that I want to use the reticle any differently than its original intent with a 100 yard/meter zero, because the subtensions on the bullet drop compensator are regulated for that zero.
Question:
With that in mind, is it there anything tactically unsound about using the 50 yard zero for my iron sights (should the scope become damaged), while maintaining the 100 yard zero for the 4X optic? Alternatively, has anyone ever worked out what the subtensions on the Trijicon TA31F's bullet drop compensator would work out to with the scope zeroed at 50 yards? I realize that the ballistics would be unchanged for the cartridge;, but for instance, what would the 400meter mark on the BDC work out to with a 50 yard zero?
I'm an old poop with the older Mark 60+ eyeballs, and I can't really see a target that clearly beyond about 50 yards without magnification (and/or glasses). This particular carbine is a both a general purpose/hunting carbine (Texas hogs and whitetail) as well as my SHTF weapon. God willing and the creek don't rise, I'll never need iron sights. I really like the idea of the 50 yard zero and its flatter shooting trajectory out to real-life distances. I'm just wondering if it is at all worth it to do that with the Trijicon.
Oh I know man. This thread is top notch! Some guys just need the simple part explained with crayons and a white board. I have had to explain the fact that bullets do not generate "lift" and flight like the foil on wings to too many buddies. Figured some guys would "get it" with the explanation.
I have heard a few people talk about certain bullets/cartridges that "rise" when they leave the barrel. Even when I was new to rifle shooting, I knew that was against the laws of physics. Still, plenty of people operate under that confusion.
The Annoyed Man
05-02-14, 07:59
I have heard a few people talk about certain bullets/cartridges that "rise" when they leave the barrel. Even when I was new to rifle shooting, I knew that was against the laws of physics. Still, plenty of people operate under that confusion.
Apparently, they have not ever heard of parallel and converging axes, nor of gravity. :p
Apparently, they have not ever heard of parallel and converging axes, nor of gravity. :p
That's a bunch of liberal nonsense.
That's a bunch of liberal nonsense.
Thanks for the morning laugh.
Having read this thread and others, it seems no particular zero is perfect, or better than another. it's all about choosing a specific zero, sticking with it, and knowing your dope at different distances based on your chosen zero.
Still, I think one does need to consider what is the most likely scenario they might have to use their AR to defend themselves, and zero for it.
This thread makes me more anxious to ditch my aimpoint clone (lower 1/3rd) and get back to an Eotech (co-witness) next month. I like having concrete ballistic data points that are supported by my chosen optic, rather than screwed up by it.
Has any ever tested to see what the POA/POI differences are between lower 1/3rd and absolute co-witness with different distance zeros? I can't imagine it would be much.
Thanks for the morning laugh.
Having read this thread and others, it seems no particular zero is perfect, or better than another. it's all about choosing a specific zero, sticking with it, and knowing your dope at different distances based on your chosen zero.
;)
That's what we do. Just stick to a 100 yard zero and when we jump from gun to gun we already have an idea of the come up for that caliber as we work out to longer ranges.
Has any ever tested to see what the POA/POI differences are between lower 1/3rd and absolute co-witness with different distance zeros? I can't imagine it would be much.
You can plug in sight over bore variances in to trajectory programs. I mess with the program before and sight height was very negligible.
;)You can plug in sight over bore variances in to trajectory programs. I mess with the program before and sight height was very negligible.
I figured as much. Although logic would dictate that the POA/POI differences are magnified at longer distances.....right? Or.....no.....the difference would remain constant? No....no....a slight difference at, say, 25 yards would be magnified at 200 or 300 yards?
Coffee....where's my coffee......muh brain ain't workin'.
Failure2Stop
05-02-14, 10:40
I figured as much. Although logic would dictate that the POA/POI differences are magnified at longer distances.....right? Or.....no.....the difference would remain constant? No....no....a slight difference at, say, 25 yards would be magnified at 200 or 300 yards?
Coffee....where's my coffee......muh brain ain't workin'.
Line of sight difference between absolute and lower 1/3 cowitness makes zero practical difference.
Cincinnatus
05-19-14, 20:36
I had a commercial carry handle laying around, so...
In order to "adjust" a commercial-height carry handle sight to mil-spec height, and then be able to back it down for the 100 yard zero, I am doing this:
I loosened the detent screw so as to adjust the elevation wheel separately, just like when adjusting for RBZ, but instead of dialing the drum down, I dialed it up the .40 to where it is equal to the mil-spec height, then re-tightened the screw. Now my starting point is the 6/3 point (with number dial labeling it thus), just like a mil-spec carry handle. Now I dial it counter-clockwise 8 clicks (removable carry-handles are supposed to receive double the clicks of an A2 sight): this should now be the point for my 100 yard zero, correct?
The only downside (besides potential quality problems with a commercial carry handle) that I can think of so far, is that now my maximum dial-in range for the sight is now about 575 yards instead of 600 or beyond, as it is with a mil-spec carry handle.
Does this "fix" work the way I am thinking it does, or are my computations way off?
Doc Safari
05-23-14, 10:25
I have recently become a real fan of the RIBZ. 6/3 -4 clicks at 50 with the detachable carry handle. I would love to see a chart or table to simply list in "number of clicks" clockwise from 6/3 -4 (or from just 6/3) to use for each subsequent elevation setting. Not that I'll be doing much shooting at 400 yards, for example, but some of the charts and graphs can be somewhat mind-boggling at the same time they are informative.
Failure2Stop
06-29-14, 13:36
Looking for custom turrets? Take a look at these TURRET LABELS for about $25.00.
http://customturretsystems.com
Those are pretty neat, but aren't really applicable to this thread. I'd recommend posting in the optics sub forum.
suggestions: add elevation and drop next to POI, add a few dimensions for the target, and maybe move POA to the head (the dot I drew is 2 MOA at 100 yards)?
Great graphics but I would still suggest everyone to actually go out and confirm the longer ranges (if available) and not just assume where your POI will be when zeroing at 25 or 50 yards.
http://i.imgur.com/oLPU9h1.jpg
jaybirdritenour2
03-28-15, 20:54
Can you do the 10.5 with 400 and 500 added, both 55 and 62 gr? Might go to the 500 yard range and try to see how I can do at that distance with it. Add fake legs.
Christopher
05-12-15, 19:53
Thought this might assist in getting a better m4 zero in low light conditions or persons who have a hard time seeing the target. PM me with your email if you would like the file so you can print and use this target.
http://i705.photobucket.com/albums/ww58/reaperpaintball08/M4SightinModified.jpg
Are you still offering to email the file for this target? Thanks in advance.
**Edit** Found some target threads. Thanks !
Molon: what software did you use to create the ballistics graphs in your posts?
Molon: what software did you use to create the ballistics graphs in your posts?
Oehler's Balistic Explorer
Doc Safari
07-27-15, 14:32
I'm trying to explain to a young shooter what to adjust to get an approximate 50 yard zero by telling him how many clicks to move the front sight. He wants the irons for 50 yards and less, and will use some kind of optic for anything further. The reason for knowing how much each click of the front sight results in what change in POI is because he doesn't want to be out there all day wasting ammo!
Right now he's got a 16-incher with standard front sight post and the carry handle. I had him check to make sure the base of the front sight post is flush with the opening in the front sight base--check.
He says that at around 50 yards this results in a POI somewhat higher than the target. I told him to go measure how much higher while I ask you guys how much of a shift in point of impact occurs at 50 yards with each notch in the front sight post.
We are NOT talking IBZ or RIBZ, but leaving everything stock. I also believe we are talking .223 pressures and not 5.56 ammo.
Are the adjustments different for a standard A2 sight on a carry handle versus, say, a Magpul rear BUS?
Awesome! But where's the 75 gr data?
(sorry, I had to ask...)
I didn't want this thread to get too complicated, so I just used the ubiquitous M193 and M855 for examples. I'll post another thread with reams of 75 grain data.
.....
The zero changes with every barrel length/muzzle velocity change....
If you understand the concepts you should be able the figure out your near-zero/far-zero points from a ballistic calculator, which you can find on the web....and your own particular rifle/ammo combination.
I'm trying to explain to a young shooter what to adjust to get an approximate 50 yard zero by telling him how many clicks to move the front sight. He wants the irons for 50 yards and less, and will use some kind of optic for anything further. The reason for knowing how much each click of the front sight results in what change in POI is because he doesn't want to be out there all day wasting ammo!
Right now he's got a 16-incher with standard front sight post and the carry handle. I had him check to make sure the base of the front sight post is flush with the opening in the front sight base--check.
He says that at around 50 yards this results in a POI somewhat higher than the target. I told him to go measure how much higher while I ask you guys how much of a shift in point of impact occurs at 50 yards with each notch in the front sight post.
We are NOT talking IBZ or RIBZ, but leaving everything stock. I also believe we are talking .223 pressures and not 5.56 ammo.
Are the adjustments different for a standard A2 sight on a carry handle versus, say, a Magpul rear BUS?
The type of ammo and pressure will not change the amount of elevation or windage change per click of the sights.
With a 16" barrel the elevation change is about 0.8" and the windage is about 0.4" at 50 yards.
ghosttwofive
09-10-15, 20:22
This is one of the most informative posts I have ever read. Thank you for the info.
LaughingWolf
11-08-15, 17:47
This is an awesome thread but I've still got a question. I was a 249 gunner from 2008-2015 and I had an acog issued to me. I zeroed at 100 meters, confirmed it every six months, was good to go.
I just bought an acog for my ar15, and living in the people republic if illinois, was able to find a 75 yard range. I used the zeroing target for m4s with acog for a 25 meter zero so I should be on the money for 100 meters; but what I'm trying to determine is what should the distance between the point of impact and point of aim for an acog firing at 75 yards (until I can find a 100 meter range)
Thank you all!
Sent from my SCH-I545 using Tapatalk
This is an awesome thread but I've still got a question. I was a 249 gunner from 2008-2015 and I had an acog issued to me. I zeroed at 100 meters, confirmed it every six months, was good to go.
I just bought an acog for my ar15, and living in the people republic if illinois, was able to find a 75 yard range. I used the zeroing target for m4s with acog for a 25 meter zero so I should be on the money for 100 meters; but what I'm trying to determine is what should the distance between the point of impact and point of aim for an acog firing at 75 yards (until I can find a 100 meter range)
Thank you all!
Sent from my SCH-I545 using Tapatalk
What ammunition are you zeroing your weapon to shoot?
LaughingWolf
11-08-15, 23:14
What ammunition are you zeroing your weapon to shoot?
55grain m193.
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Failure2Stop
11-09-15, 09:21
This is an awesome thread but I've still got a question. I was a 249 gunner from 2008-2015 and I had an acog issued to me. I zeroed at 100 meters, confirmed it every six months, was good to go.
I just bought an acog for my ar15, and living in the people republic if illinois, was able to find a 75 yard range. I used the zeroing target for m4s with acog for a 25 meter zero so I should be on the money for 100 meters; but what I'm trying to determine is what should the distance between the point of impact and point of aim for an acog firing at 75 yards (until I can find a 100 meter range)
Thank you all!
Sent from my SCH-I545 using Tapatalk
http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi
http://appliedballisticsllc.com/ballistics/
About 0.8 inches below POA at 50 yards, about 0.3 inches below POA at 75.
LaughingWolf
11-09-15, 17:23
You all rock! Thank you!
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I realize this is old ground for most; however, I have my personal rifle zeroed at 50 yards, thus giving me my second zero at approximately 200 +/- (I can't recall the exact distance, seems like it was around 220). However, my tactical team insists on zeroing ALL rifles (5.56 and .308) at 100 yards. Their reasoning? If you're zeroed at 100 yards, anything you'd be justified in engaging that's over 100 or under 100, you know you need to "hold over" with your point of aim. I know a 100 yard zero is pretty standard on sniper rifles for tactical teams, and I'm sure we'll be stuck to that for a while.
But on the 5.56 rifles, it makes more sense to me to zero at 50 yards and then you know whatever your point of aim from about 10 yards out to about 220 yards, your point of impact should only vary from about 1.5" either above or below point of aim. In a high-stress situation, place the red dot on your target and shoot - don't goof with trying to remember how much you need to hold over at a certain distance.
Does anybody have any experience or caveats with the two zeros and their practical use in a tactical environment? I've made my case a few times, but it always seems to return to the old adage "this is how we've always done it and we're comfortable with it."
Thoughts?
I do. I was at the range at least twice a week with my rifles. Everything from running drills to bangin steel at 600 with the M4 and the Shawty. I had both rifles zeroed at 50yds. The M4 an 11.5" ran T1s but the M4 had a 3x magnifier. The KiNo had an A2 carry handle.
Anyways the reason I zeroed at 50 was because of the trajectory as well. The best advice I can give is shoot your rifles often and get to know exactly where they hit. I knew exactly where I had to aim or hold over at certain distances because I trained often with my rifles.
It's hard to understand how guys can zero it once and take it to the range once every 6 months and still use these at their home for defense or SHTF whatever.
The only way to know your weapon is to train with it. Too much difference in ammo,barrel length etc to ask someone "where will my bullet go if I Zero at 25?" Go shoot it an learn.
I completely agree, and I do have comfort in knowing we shoot often and know our rifles pretty well. It just seemed to me there's less opportunity for error in a SHTF scenario with a 50 yard zero. Thinking along the KISS lines, I like to take as many variables out when possible.
I love that zero. When it came to versatility it works great. Couldn't have been happier with the drills even at 15 yards....on point. Anything out to 50 was perfect. The T1 I had was the 4moa. Accuracy was on point. Head shots were right where I put them.
The benches were about a hundred yards to the right, I didn't have to touch anything. For head shots at that distance, my POA was about 6" and with a 4moa dot, it was about the reticle height.
300 yards took a little more patience but was still easy after walking it in.
600 got to be difficult in two ways. One was the wind, in the sense of not being able to hear the 62 grain round smack the plate....two was holding over. The dot completely covered the man sized silhouette steel,mwhile didn't matter since I was holding over about 10'. I know it was more than that but at that distance it was hard to gauge
Good stuff to hear. I haven't used my 5.56 with that zero past 300. Like you, I've got an Aimpoint on it and find you really start needing some magnification for repeated hits and consistency out at distance. Usually whip out the .308 for work past 300. I'll have to give it a whirl though! Thanks for sharing your experience.
Thoughts?
From my original post of this thread . . .
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.
http://www.box.com/shared/static/dff892e7179fa7e265a7.jpg
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.
...
lethal dose
02-24-16, 15:13
Hope all's well, guys. I've reviewed the thread for performing a 100 yd zero on an A2 upper, but don't understand how to translate it to an A2 detachable CH. Can you give me a few pointers? Many thanks.
Hope all's well, guys. I've reviewed the thread for performing a 100 yd zero on an A2 upper, but don't understand how to translate it to an A2 detachable CH. Can you give me a few pointers? Many thanks.
from the original post:
* E.T.A.
All click references should be doubled when using detachable carry handle sights.
Molon not sure if this was covered here. Just wondering what you think of this. And what distance do you use for sighting in?
http://www.thenewrifleman.com/maximum-bullet-flight-getting-the-most-out-of-ar15-zero/
lethal dose
02-27-16, 04:54
from the original post:
I should have expounded. I saw that and, unfortunately, I simply don't understand it. If you don't mind, could you spell that out in a bit more detail? Thanks!
I should have expounded. I saw that and, unfortunately, I simply don't understand it. If you don't mind, could you spell that out in a bit more detail? Thanks!
Try this:
We are only talking about carry handle style rear sights. With fixed carry handle sights, the lowest marked elevation setting is (usually) "8/3". When you turn the elevation wheel clockwise to get to the marked setting "4", there will be THREE distinct clicks, or stopping points. The third one is at marked setting "4".
If you are using a removable carry handle, the lowest marked setting is usually "6/3". When you turn the elevation wheel clockwise to get to setting "4", there will be SIX clicks, or stopping points, with the sixth one being the setting marked "4". In other words, there are double the number of clicks (compared to fixed carry handles) to get from one marked elevation to the next marked elevation.
I have heard of removable carry handles with the fixed carry handle-standard three clicks between "3/6" and "4", but those are unusual.
This is important for the RIBZ because, when you adjust the rear sight settings so that the marked settings are shifted and your lowest possible setting is now FOUR clicks counterclockwise from the "3/8" setting, it will usually require EIGHT clicks of counterclockwise adjustment from "3/6" to have the same result with removable carry handles.
lethal dose
02-27-16, 06:36
There's not an emoji that indicates something going way over its head, is there?
Try this:
We are only talking about carry handle style rear sights. With fixed carry handle sights, the lowest marked elevation setting is (usually) "8/3". When you turn the elevation wheel clockwise to get to the marked setting "4", there will be THREE distinct clicks, or stopping points. The third one is at marked setting "4".
If you are using a removable carry handle, the lowest marked setting is usually "6/3". When you turn the elevation wheel clockwise to get to setting "4", there will be SIX clicks, or stopping points, with the sixth one being the setting marked "4". In other words, there are double the number of clicks (compared to fixed carry handles) to get from one marked elevation to the next marked elevation.
I have heard of removable carry handles with the fixed carry handle-standard three clicks between "3/6" and "4", but those are unusual.
This is important for the RIBZ because, when you adjust the rear sight settings so that the marked settings are shifted and your lowest possible setting is now FOUR clicks counterclockwise from the "3/8" setting, it will usually require EIGHT clicks of counterclockwise adjustment from "3/6" to have the same result with removable carry handles.
There's not an emoji that indicates something going way over its head, is there?
My last try with an analogy:
Imagine a car with a three speed transmission: low, medium and high gears. To get from 0 to top speed, you move through three gears.
Now, imagine the same car, but with a six speed transmission. To get from 0 to top speed, you move through six gears. You are not going any faster than with the three speed transmission, but you have to go through DOUBLE the number of gears.
Just wondering what you think of this.
http://www.thenewrifleman.com/maximum-bullet-flight-getting-the-most-out-of-ar15-zero/
Not much.
From the article: “Typically M193 is considered a 1.5 to 2 MOA bullet. . .”
That statement alone, demonstrates his lack of knowledge/experience on the subject matter.
My evaluation of four different M193 loads (at the link below) shows that M193 loads only average approximately 3 MOA . . . and that evaluation was conducted using heavy barrels shot from a bench-rest; not standard barrels shooting from field positions.
Attack of the (M193) Clones (https://www.m4carbine.net/showthread.php?62632-Attack-of-the-(M193)-Clones)
Also, his thinking is based on shooting at old-fashioned B-27 targets. That’s another indicator of his lack of knowledge/experience on the subject matter.
B-27 target . . .
https://app.box.com/shared/static/bdg4xdkvqxn9fnxy2f7dgirunc9tywms.jpg
How often does an armed criminal/enemy combatant who is intent on inflicting death or grave bodily harm on a law abiding citizen/law enforcement officer/soldier, stand out in the open, squarely facing you, with his hands at his side and holding perfectly still (which is what is depicted in a scenario with the unrealistic B27 targets) while allowing you to shoot at him and all the while not shooting back at you?
The Front Sight target pictured below is an “accurate representation of human dimensions taken from medical cadaver studies and 3000 x-ray studies.” This target represents a much more realistic aiming area that you would have available to shoot at on a criminal/enemy combatant who is shooting at you from behind cover. As you can see, the room for error on the part of the law abiding citizen/LEO/solder is far smaller with this target than that depicted in typical law enforcement/military training targets; particularly since our objective is not “just to hit the target,” but to make multiple center of upper thoracic cavity/central nervous systems hits (depicted by the “5” scoring zones on the target below).
https://app.box.com/shared/static/xkl2x62g0lrqi9g4osukazrcdh7a9kqb.jpg
..
Try this:
We are only talking about carry handle style rear sights. With fixed carry handle sights, the lowest marked elevation setting is (usually) "8/3". When you turn the elevation wheel clockwise to get to the marked setting "4", there will be THREE distinct clicks, or stopping points. The third one is at marked setting "4".
If you are using a removable carry handle, the lowest marked setting is usually "6/3". When you turn the elevation wheel clockwise to get to setting "4", there will be SIX clicks, or stopping points, with the sixth one being the setting marked "4". In other words, there are double the number of clicks (compared to fixed carry handles) to get from one marked elevation to the next marked elevation.
I don't know that I can explain it any better than Amicus just did. The only other thing I can suggest is to find find someone with a fixed carry handle upper receiver, and put that next to your removable carry handle sight and start playing with the elevation drums. Then maybe it will become clear after actually seeing it in person.
....
Knife_Sniper
02-27-16, 20:55
Not much.
From the article: “Typically M193 is considered a 1.5 to 2 MOA bullet. . .”
That statement alone, demonstrates his lack of knowledge/experience on the subject matter.
My evaluation of four different M193 loads (at the link below) shows that M193 loads only average approximately 3 MOA . . . and that evaluation was conducted using heavy barrels shot from a bench-rest; not standard barrels shooting from field positions.
Attack of the (M193) Clones (https://www.m4carbine.net/showthread.php?62632-Attack-of-the-(M193)-Clones)
Also, his thinking is based on shooting at old-fashioned B-27 targets. That’s another indicator of his lack of knowledge/experience on the subject matter.
B-27 target . . .
https://app.box.com/shared/static/bdg4xdkvqxn9fnxy2f7dgirunc9tywms.jpg
How often does an armed criminal/enemy combatant who is intent on inflicting death or grave bodily harm on a law abiding citizen/law enforcement officer/soldier, stand out in the open, squarely facing you, with his hands at his side and holding perfectly still (which is what is depicted in a scenario with the unrealistic B27 targets) while allowing you to shoot at him and all the while not shooting back at you?
The Front Sight target pictured below is an “accurate representation of human dimensions taken from medical cadaver studies and 3000 x-ray studies.” This target represents a much more realistic aiming area that you would have available to shoot at on a criminal/enemy combatant who is shooting at you from behind cover. As you can see, the room for error on the part of the law abiding citizen/LEO/solder is far smaller with this target than that depicted in typical law enforcement/military training targets; particularly since our objective is not “just to hit the target,” but to make multiple center of upper thoracic cavity/central nervous systems hits (depicted by the “5” scoring zones on the target below).
https://app.box.com/shared/static/xkl2x62g0lrqi9g4osukazrcdh7a9kqb.jpg
..
If I was overly generous with my example of accuracy and M193, forgive me. The crux of the article was not about how accurate or inaccurate M193 is, and if you wish substitute a reasonably accurate 55 grain bullet for the performance charicteristics of M193 cited in the article and related examples.
The evaluation and study was best surmised as "what is best practice for hitting a target at an unkown distance, under duress of time and stress"?
The ultimate conclusion is that a accurate projectile fired from a barrel keeping said projectile relatively within 1 MOA and sighting in your setup where the smallest realistic target presentation you may encounter matches the maximum ordinate of your projectiles flight path will minimizes the need to hold over and would increase the probability of hitting your target.
No where is the article inclusive to the B27 other than wind deflection examples, and in fact in studying the methods of maximum point blank range and applying them to the smallest typical target zone "the head" would permit you to put the reticle on target and should give you the greatest probability of a hit since the bullet will remain aloft in the critical zone for the longest distance between the shooter and the end of your maximum point blank range.
While a 50 / 20-225 yard zero is certainly suitable for most shooting, my question remains what is pertinent and what is not in increasing the raw probability of hitting a target with a shooter who is under stress, is tired, and may utilize sloppy technique while firing at a target who presents for a short period of time? If the target presents itself for mere seconds, how accurately can a shooter range and shoot on a exposed head as such in your example? Instead why not maximize the distance in which our projectile remains in flight with a maximum rise no greater than the chosen target diameter? It would be a useful zero for exactly what your cadaver study supposes.
Which method would allow a higher probability of a CNS hit, a conventional zero based on 100 yard increments, or a zero that takes advantage of your specific rifle, specific ammunition type, velocity, and superimposes your useful zero and its bullet rise and fall on the maximum diameter of your chosen target? I believe the maximum point blank range method of zeroing is a useful tool, and you can always tighten the rise and fall of the trajectory by going up or down a few clicks on your turrets.
In the WEZ analysis software, it has been noted that vertical uncertainty is the largest degree of influence on a shooter missing a target in a low confidence scenario, and that accurate range estimation is essential to hitting said target. While the following well written article discusses the effects of shooter error, range estimation, and atmospherics at a target pushing 900 yards, you can surmise that the a shooter in a shorter range scenario would have a higher probability of hitting the target if he /she uses match ammo with a high of a BC as achievable out of the platform, an accurate rifle to shoot it with, and a zero which eliminates *as much as possible* the need to hold over a target which presents at an unknown range. Every defensive target we encounter will be at an unknown range. The question then becomes, have I zeroed my rifle in such a manner as to give me the greatest probability of intersecting that targets critical zone with minimal need to hold over? If yes fire. Minimizing the need to hold over with say a 100 yard zero and or hold under with something along the lines of a 300 yard zero is something we should seek to avoid. It's effectively error compensation in a situation where you shouldn't have to add more solutions to the problem. If we take this at a more micro level of where you may be shooting at a partially exposed head, a exposed rifle, a leg, etc. inside of 300 yards, I believe that *reducing* the need to hold over by increasing your trajectory's effective target envelop will give you a greater probability of hitting the target, be it your cadaver scenario or a fully exposed silhouette.
http://www.nvisti.com/wp-content/uploads/2014/06/NVDOC14.02-WEZ.pdf
Each and every thing we add or subtract to our rifle ultimately increases or decreases our odds of hitting the target. A zero which increases our chances of hitting a fleeting target where the shooters need to adjust the shot is minimized is also a part of that equation. Quality ammo with a high BC adds another few percentage points with its ability to reduce wind drift and increased accuracy. All this stemmed from a relative who saw combat in Afghanistan, and went through DMR school yet, he told me how incredibly frustrated he became when targets would appear for seconds and then disappear before he could make use of any of that training or marksmanship theory. His M14 DMR was nothing special in these scenarios, he couldn't range or spin turrets fast enough before the threat would disappear. That was the impetus for my study (and continued study) of civilian marksmanship. The more and more I study this... the more I see what others have developed in regards to the "moneyball" of shot analysis, especially Brian Litz, the more it becomes apparent that hitting a target is a big game of percentage points... once you have done your part to flash that target with your crosshair or reticle, and you pulled that sloppy shot, it's all up to probability, the bullet, and its relationship in the environment as to whether it's a near miss or a hit.
Ultimately, does a maximum point blank range zero scheme add any help to the shooter at hitting a target at an unknown distance? is it 1% 5% 10% Who knows? The question is if it did give you a few points extra in hit probability, who wouldn't take it? We zero based on square ranges and 100 yard increments, yet our target will always present at an unknown range.
and no hard feelings to Molon, he has done much for our community, and I may disagree with him here and later on, but this will never resort to name calling. We play for the same team even if we don't subscribe to each others newsletter if you get my drift.
P.S. everyone. I know the furthest typical defensive distance we are likely to engage is 25 yards and under. That's not going to stop me from passing on short and long range shooting to my children. It would be negligent of me to suppose that society and our current "scenarios" and common knowledge will always be the ones that we are likely to encounter. The veil of society is thin, and easily shred...
JohnnyRambo
05-05-16, 22:32
Great info. Thanks for taking the time to post all that. Very helpful!
53dannyboy
05-21-16, 19:03
Thank you for a lot of work/research that went into this...very impressive. Do you know of such info compiled for the AR in 7.62x39mm?!
Thank you for a lot of work/research that went into this...very impressive. Do you know of such info compiled for the AR in 7.62x39mm?!
I'm afraid I don't own a 7.62 x 39mm.
jlberryhill
11-08-16, 21:07
This is absolutely fantastic and makes me think I have no idea where my bullets going to go lol. Fortunately I do confirm at range.
jlberryhill
11-08-16, 21:12
Correct me if I'm not mistaken - the KAC 600M rear is designed with the same A2 metrics/data in mind correct?
Failure2Stop
11-09-16, 07:15
Correct me if I'm not mistaken - the KAC 600M rear is designed with the same A2 metrics/data in mind correct?
Sort of, but the sight radius makes a difference in adjustment value.
Still, zeroing them at 200 meters is a highly efficient method for iron sight application.
Sort of, but the sight radius makes a difference in adjustment value.
Still, zeroing them at 200 meters is a highly efficient method for iron sight application.
Thank you.
I have a basic question. If I sight in at 50 yards and then check at 200yds and my 200yd hits are a little low or high, is there a calculation that will tell me where my actual zero is or do I need to move the target accordingly until I get zero?
Also, is it better to zero for the 200 and then offset for my 50yd POI or is it better to do the opposite? I'll assume that it depends on where I think my real world shooting distance will be, from 50 to 100 or more in the 200 range.
I have a basic question. If I sight in at 50 yards and then check at 200yds and my 200yd hits are a little low or high, is there a calculation that will tell me where my actual zero is or do I need to move the target accordingly until I get zero?
Also, is it better to zero for the 200 and then offset for my 50yd POI or is it better to do the opposite? I'll assume that it depends on where I think my real world shooting distance will be, from 50 to 100 or more in the 200 range.
Pick a zero, meters or yards. 200 meters is 218-2/3 yards. I would start at 25 yards or 50 yards, then work my way back to 200 yards. Make the necessary sight adjustments to center your shot group on target at 200. Once you have a good zero at 200 yards or meters, verify POI at 50 yards and leave the adjustments alone. Once you fine tune your zero at 200 yards or meters, I doubt you'll notice a shift in POI at 50 yards or meters. I would also shoot at distances inside 25 yards to verify how much you would have to hold over for a head shot.
Nice. I will have to get some of those targets. I am not sure exactly where my 14.5" carbine is "zeroed" with the ammo I use, but I do know that I can aim at the center of a 3x5 card (between the hairline and upper lip) and have all rounds hit the card from 0-200 yards. I also know, from shooting, not programs, that if I aim at eye level on a fully exposed "average" guy (like me) all rounds will hit under the hairline and above the belt line between 0-350 yards. This gives me a warm fuzzy.
The main thing is knowing.
Fidalgoman
02-02-17, 16:27
From my original post of this thread . . .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.
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....
I know this is an older thread but in my case my AR is a defensive weapon from a civilian POV. I tend to think of it as the Swiss do, "in case we are ever invaded" (one way or another), so to speak. Yeah I like to go punch holes in paper and take Rifle classes once in a while but it's not too hard to keep a log on elevation for longer ranges, windage, temperature and different ammo. That's what we're supposed to do, Right?
Anyway, my choice has become a 1-4 scope, zeroed to fifty meters. It is easier to zero with the lack of stellar accuracy of most of my practice ammo since the overall grouping is smaller. IMO it's optimal for my use. Most important is the zero of my defensive ammo.
As a side note last year I spent several trips to the range in very cold and sometimes blustery conditions. Slow fire through one mag and then sit in the car for ten minutes until I could feel my fingers, then do it all over again for about 200 rounds. I did this to condition myself for extreme conditions. Funny though, I seemed to be the only person taking advantage of the weather.
Since my rifle was keeping zero I didn't bother to zero it for a 0-50 yard class I took in the spring. Surprise, with the warmer weather I had to re-zero well over an inch at fifty yards. The main point is there are a lot of factors that effect accuracy, my ammo was below zero during my winter forays and around seventy for the class. It was from reading this thread a couple years ago that convinced me that fifty meters was ideal for my purposes. YMMV. Thank you.
Thanks for the original post! I followed the directions you so clearly gave on my old Colt removeable carry handle (6/3) for RIBZ, sighted a tight group at 25 and watched the magic as I clicked for the 50 and 100 yard zeroes. So handy.
Sent from my Pixel using Tapatalk
SMASHING MACHINE
04-11-18, 18:59
Some great info here. Thanks for the education.
RetroRevolver77
11-03-18, 21:54
deleted
SOL-INVICTUS
12-01-18, 14:47
Worth noting during these discussions is the correct use of both the ghost and peep apertures. Without going into the neuropsychological and perceptual weeds. When using your ghost ring, large aperture, you focus on the target and the post will center. When using the peep, small aperture, focus on the front sight and the post will center. In both cases do not pay attention to trying to center the post your visual cortex will do it for you provided you focus the target or the post as noted.
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lordmorgul
12-01-18, 21:33
300 meter zero at 100 yards for a carbine is what about 5" high at that distance? I ask because almost all the AR zeros are based on 25 meter, 50 meters etc. While I used to have access to ranges that allowed rifles on the pistol ranges- that isn't the case anymore.
Approx 4” depending the bullet/load, but it will not have reached its apex yet and that happens around 175yd at 5”.
Andrew - Lancaster, CA
NRA Life Member, Calguns.net contributor, CGF / SAF / CRPA / FPC / NRA-ILA contributor, USCCA member
SOL-INVICTUS
12-03-18, 15:42
Those with carbine or shorter length barrels with the Non F marked front sight may want to consider the .06 post from Windham Weaponry. They have a kit with the extended .04 and .06 along with standard post and the adjustment tool. The .06 is the ticket if you want to do the RIBZ zeroed at 100 yards 6/3 -6 (-7 with buffer) and detachable carry handle. Must have if want to shoot the 62 gainers due to their higher point of impact.
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This is a really great thread and the tutorial is awesome. I would bet a lot of money, at least $5 that the 25 meter zero was chosen because it is easier to do both in practice and logistically and faster. Plus teaching a private to shoot sucks!
I'm not sure how I missed this thread earlier, but I found it today. The opening post is an absolutely great explanation of nearly everything about "zeroing" an AR.
One fact that appears several times in the original post is especially important to evaluating or discussing ANY zero:
"this is only with a very few particular combinations of bullet weight, barrel length/muzzle velocity and height of sights above the bore" we too often forget that this is true of every zero in every gun.
Never knew there was so much difference. Thanks for posting this.
Thanks for posting this! I've benefitted from it quite a bit over the years.
This is great info for a newbie owner.
Links and images don't show for me, is anyone else able to see them? If not, can we get uploaded or nuke this thread?
Links and images don't show for me, is anyone else able to see them? If not, can we get uploaded or nuke this thread?
We just went through this in one of the other threads. I'll see if I have these one. Not so sure if I do.
Links and images don't show for me, is anyone else able to see them? If not, can we get uploaded or nuke this thread?Hey Stick,
Turns out I don't have any from this thread, seems I could only see 2 activate links from this thread. If it helps at all, I do have the ones this other thread:
https://www.m4carbine.net/showthread.php?p=2928865
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kenboyles72
07-18-21, 21:55
Links and images don't show for me, is anyone else able to see them? If not, can we get uploaded or nuke this thread?
I saved this thread a while back locally on my pc for future references. While I did save it, I didn't get all the images, but most is there. I can put it in a zip and send it to you or anyone else that needs it.
Edit:
Went ahead and zipped it up, got it hosted in google drive. Someone can use that and edit the original posts as much as possible.
https://drive.google.com/file/d/17CO8yjeju-IS3cO8GdkIfhxT-Ka3xi8U/view?usp=sharing
Not sure how I missed this for... SIX YEARS - scratch that - *ELEVEN* Years.
Is there any way to get the attachments to show up again?
Thanks, Molon!
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Lt. Col. Chuck Santose' article on IBZ in PDF format.
Once I came across the IBZ, I tried it and have been using it ever since.
Lt. Col. Chuck Santose' article on IBZ in PDF format.
Once I came across the IBZ, I tried it and have been using it ever since.
Thanks, T2C.
I remember ordering several of those some years ago.
Though I cannot put my hands on it now I never threw them out.
Ahh... I have a bag with optics and external ballistics info. So I have them.
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Is there any way to get the attachments to show up again?
https://web.archive.org/web/20160403042528/http://www.m4carbine.net/showthread.php?65679-ar-15-zeros-and-trajectories
Donate to web.archive.org if you find this useful.
https://web.archive.org/web/20160403042528/http://www.m4carbine.net/showthread.php?65679-ar-15-zeros-and-trajectories
Donate to web.archive.org if you find this useful.
Thanks, brother.
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I see 25 pages. Extremely worded explanations. No bottom line. What is the best zero?
Sidneyious
02-20-23, 20:28
I see 25 pages. Extremely worded explanations. No bottom line. What is the best zero?
DeltaThirtyFour did a really good breakdown, use it as you wish.
https://youtu.be/9qkKJyMtpVI
https://youtu.be/HFE-wj7sOs0
titsonritz
02-20-23, 22:54
I see 25 pages. Extremely worded explanations. No bottom line. What is the best zero?
Define "best".
There is no bottom line, choose which is best for your application, know it and work it.
I see 25 pages. Extremely worded explanations. No bottom line. What is the best zero?
I've tried a 100 yard zero, 200 yard zero and 300 yard zero and used all of them extensively. I keep going back to the 200 yard zero, because it works best for me for engaging targets from 5 yards to 300 yards.
StainlessSteelRat
02-23-23, 17:39
I've tried a 100 yard zero, 200 yard zero and 300 yard zero and used all of them extensively. I keep going back to the 200 yard zero, because it works best for me for engaging targets from 5 yards to 300 yards.
Not a SME of any sort, but I second this. Neck to nuts coverage from shoelaces out to about 300, as they say. Being able to get quick torso hits at practical ranges is what I was looking for.
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