I also run a 50 yard zero and I have no issues shooting from 5 yards to whatever (100 max usually). I loaned a rifle to a guy at the IPDA yesterday and he could not get the hold over right at close range. I kept telling him to aim 3'' high and he didn't so all his shots were super low.

thank you op for this thread. I will use the chart tomorrow at the range for my 300 yard shots at gongs. i am guessing ill be somewhere around 5 inches low at 300 yards with a 50 yard/200 meter zero

That would depend upon your barrel length and load.





 

Well ill be shooting 55 grain out of a 16 inch barrel so i think a hold 5 inches high would get me in the ball park at 300

M-193 would be ~6" low at 300 yards.



 

Good stuff! Great info for maximum accuracy. Well done

I love these trajectory graphs. I find myself taking them to the range now and then. Great stuff Molon, keep it coming.

This thread is full of win! This makes me want to go back to my flat top upper and grab a carry handle. I'll have to pass this info down to a couple of buddies that own A2 rifles and carbines.



Once again, thank you good sir for this 1 metric f*ck tonne of information.


 

I ran into something today that I have been trying to rationalize.

My DPMS Oracle 5.56 zeroed at 100yds, groups 1in and less.

Went to 200 yards, my scope has bullet drop reticle, I aimed it the bulls eye and instead of hitting low the rounds went high and hit in the 9 and 10 ring instead of dropping below the bullseye.
Using 17.25" target, set for 200yds and beyond, and if I aimed at the bottom of the target I would hit in the bullseye and 5 ring.

Great info!

Do you have an Anti Cant Device (aka bubble level) on your scope to ensure you are level when shooting at both ranges?



 

tag for later

Great thread gentlemen.  Thanks OP.

Great post! Why is this not tagged? Very useful info Nice job Molon!

What a GREAT post! Why is this not tagged???????

I run a 50 yard zero. Seems as though this is the best for 50-200 yards.

This is such a great post - is there any way we can fix the dead images?

Which ones are dead?

http://www.ar15.com/forums/t_3_16/687996_Range_Report___PMC_5_56mm_62_Grain_X_TAC_Ammunition.html




....

Supplimetary reading:

Ribz is economical, but I found that there are several supplementary points to those seeking to improve their marksmanship accross the board regarding zeros , equipment, and the 5.56.

Let's talk about irons first. Having a M16A2 clone, I have utilized ribz, but eventually found a better iron sight solution for the fixed carry handle by upgrading to a 1/2 minute x 1/2 minute national match rear sight and ditching the 0-200 / 300 marked rear aperture ( or the hooded peep that comes with the NM sights) with a blackhawk same plane aperture. This is the setup I used to shoot my first NRA High Power match with a mil-spec M16A2 clone. I tend to try and keep my rifles more general purpose than overly specialized to fit a particular sport, so this setup keeps me well within "fighting rifle" specifications.





Above: A Armalight NM sight in 1/2x1/2 thread pitch. Below: A stock USGI A2 rear sight in 1 minute by 1/2 minute windage.



While more expensive than ribz, for those building a rifle for iron sight shooting may appreciate the quality of a NM sight and the improved tracking / fit and finish of the sight. FOR those people who are running a detachable carry handle rig you already have a 1/2x 1/2 so simply replacing the aperture with a black hawk same plane will allow you to use ribz and keep the same zero for both apertures.

Match your Optics and Irons

Variables typically come in three flavors: typically 1/2 x 1/2 or 1/4 x 1/4 or 1/10 mil

I tend to buy 1/2 x 1/2 variables to keep all my rifles within the same click values to help me keep track of dope accross the board. I shoot systems ranging from 16 to 20 inches and thus keep my loadings within similar velocity range. I shoot M193 as a primary cartridge for all rifles since it is easily stacked deep and cheap. I then shoot a 75 grain load under 24 grains of Varget that matches the trajectory of M193 provided you zero the 75 grain cartridge at 200 yards.



Having both irons and optics share the same loadings/dope vastly improved my ability to keep track of all my shooting. (Mind you, my irons click values match the optics, and my irons are set up on a 20 inch rifle so the values aren't skewed by the shorter radius of carbine length platforms.)

Furthermore, each system is zero'd at 100 yards. From here, I can work up to whatever zero meets my requirements. A few clicks up can get me from 100 yard zero, to a 200 yard zero, to a zero at maximum point blank range, to a 300 yard zero, etc.

Of particular value to me is MPBR where I use my calculator to find the dope where my cartridge will rise 3 inches at maximum ordinate. This is well within acceptable tolerance of my typical b27 targets / headshots and gives me more room to let the cartridge intersect my target without changing holds. Its up to the shooter to determine his / her comfort level for the varience in their MPBR. A 4 inch rise may be okay to some, but too wide a margin for others. I used to calculate out 2 inches vertical rise, but have since moved to 3 inches of vertical rise as my MPBR will then match a 6 inch diameter target.

This method gives you more distance on your target over a 50 yard zero yet is not so aggressive as a 25/ 300 meter / yard marine battle zero that the bullet may travel over the targets head for example due to the 8 inch maximum ordinate.

This MPBR, in effect, becomes my battle sight zero.

The biggest downside to a maximum point blank zero is that it will be different based on barrel length and cartridge. Each rifle shooting each loading with different barrel lengths will require a different amount of elevation to achieve a MPBR and if not shooting a factory cartridge such as M193 or XM855 where the velocity values by barrel length are somewhat well known due to charts like what Molon has provided for us... If you use a new loading your gonna need a chronograph and a ballistic calculator to determine your MPBR.

This is why I shoot m193 though it's a weaker round terminally then some of the newer moar better products. I can buy it at walmart and all my long guns eat it like candy. This is also why I shoot my loading which mimics the trajectory of M193 (as long as I zero it at 200 yards) while having more energy. Note I said mimics as they are close but not exactly the same. I think most people would argue that MPBR is not worth the trouble of calculating and chronographing a loading to determine vs a 50 yard zero. Statistically, most of us would do just fine with a 100 yard zero in any self defense situation we could imagine, but the beauty in the study of the rifle is that we can never over study the ballistics associated therin, only understudy which is simply a point where a knowledge deficit exists which will give you no advantage should you be taken out of your comfort zone.  

The beauty of MPBR is that we can let our target define our effective range instead of focusing on zeroing based on typical gun range 100 yard increments. Instead of, I have a 100 yard or 200 yard zero... we instead zero at 100 yards, chronograph our load, and let our calculator address the MPBR to determine how far we can hold dead center of our choice of target, and still intersect it. Instead of thinking about "is my target 200 or 250 or maybe 300 yards away?" we can instead focus on the question, is the target inside of my MPBR?

This simplifies ranging in that we no longer need to define our target in incremental distances, so instead we judge if he is inside the MPBR, or outside the MPBR. With M193 out of my 18 inch barrel and a 3 inch maximum ordinate (targeting a 6 inch diameter target) we can aim dead hold on a headshot out to about 300 yards. So I can ask, Is my target within 300 yards? Yes? Aim point of aim point of impact. Aim at the chest or head. Is my target outside of 300 yards? If yes and they are a fully exposed torso, aim at the head. Drops will be into the torso from 300-450 ish yards if I recall. I think this is the beauty of MPBR and velocity. Its also the beauty of simplifying on holds vs making them more complex. Relying on BDC reticles is not always pertinent if the target is not facing you, or only exposing a head for example.

What if the target appears for a short time before we put the crosshairs on the target and mash that trigger? What increases our chance of hitting the target, a zero that relys on our understanding and proper judging of the targets distance to successfully hit our fleeting target (such as a ACOG and BDC shooting at a head for example) or one which allows the projectile to remain aloft in the defined area of our target for the longest distance possible? This cuts down on the shooters need to estimate 100-200-300 yard holdovers on small targets of opportunity, and instead put the crosshairs on the target and pull the trigger.

Thus the end of my thoughts on rifle zero's ...

This is why all my rifles are sighted in at 100 yards, and why all my scopes are 1/2x1/2 minute adjustments. They all sit zero'd at 100 yards. If I am involved in a home invasion, I'm ok with 100 yards. If situations change, I can choose the zero which will serve the situation best. My 18 and 20 inch guns share the same dope card, and my 16 inch rifle is only a few clicks of variance to the rifles with the slightly longer Barrels. They all share the same settings so I can increase my knowledge of what I already own, and share it between different rifles. Each is ready to be adjusted up to MPBR with my loadings if shit hits the fan. Each can be precisely adjusted for targets at known ranges if I have the time to calculate that out.

For some loadings and barrel length combinations, your maximum point blank range may very well be a 200 yard zero, but that tends to happen as you shrink barrel length.

Thank you for sharing your perspective, Knife _Sniper. You seem to have found a system that really works well for you.

If you think that the average shooter has a high probability of making a shot on a 6” target (head-shot) at 300 yards (which is 1.9 MOA) on demand, while firing from a field position using an iron-sighted AR-15 (with a 12 MOA front sight post) with a MPBR zero using XM193 ammunition, you are incredibly optimistic.

To demonstrate, let’s use an example of an iron-sighted AR-15 with an 18” barrel with a NATO chamber and a MPBR zero (3” maximum ordinate) and shooting XM193 that you can “buy at Walmart”.  For this exercise, we’ll pretend that a full 6” of the aggressor’s head is exposed, (which it won’t be when the  aggressor is shooting from over/around cover or in a defilade position) and that you’re holding on the center of the head (“dead hold” as you called it.)

If everything goes absolutely perfectly, that is, your ammunition follows a perfect trajectory for every shot, your hold from your field shooting position is perfect for every shot, your sight alignment and sight picture are perfect for every shot and your trigger pull is perfect for every shot, then your point of impact at 300 yards will be 3.32” below your point of aim; you will have already missed your 6” head target.  Your bullets are  going into the dirt or impacting the cover that the aggressor's body is behind.  And again, this was if the full 6” of the aggressor’s head was actually exposed.

Now, in the real world, everything isn’t going to go perfectly.  The XM193 ammunition isn’t going to follow a perfect trajectory for every shot.  When tested from my bench-rest rig, using a free-floated heavy barrel with chrome-lining and a NATO chamber, and sighting with a 25X scope, XM193 had an average 10-shot group extreme spread of 3.27” for three 10-shot groups fired in a row from a distance at 100 yards.  If this extreme spread were to be maintained out to 300 yards, you would have an average extreme spread of 9.8” at 300 yards.

This all means that approximately 50% of your shots are going to impact below a perfect trajectory; 4.9” below a perfect trajectory.  So now, instead of your shots just impacting 3.32” below your point of aim at 300 yards, approximately 50% of your shots are going to impact between 3.32” below your point of aim and 8.22” below your point of aim.  You’re now missing your 6" head target approximatley 50% of the time, with approximately 50% of your shots impacting between 0.32” and 5.22” below the bottom of your 6” head target.  Also, these errors will be exacerbated when using shorter barrels.  All this doesn’t even include the percentage of shots that will fall outside of the 6” head target, impacting either to the left or right of the target just due to the 9.8” average extreme spread of the XM193 ammunition at 300 yards and of course this is all predicated on a perfect no-wind condition.

And again, this was if the full 6” of the aggressor’s head was actually exposed and again this isn’t taking into account the errors induced by an imperfect hold from a field position, an imperfect sight alignment, an imperfect sight picture and an imperfect trigger pull.

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 your 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).

Attached File


Again, we’ll use an example of a NATO chambered, 18” barreled, iron-sighted AR-15 using XM193 ammunition with a MPBR zero.  Not even taking into account the errors that will occur due to ammunition that doesn’t follow a perfect trajectory for every shot and the errors induced by an imperfect hold shooting from a field position, an imperfect sight alignment, an imperfect sight picture and an imperfect trigger pull; holding on the center of the head of the realistic Front Sight target at 450 yards (with a 12 MOA front sight post) will result in a bullet point of impact that misses the bottom-most torso portion of the Front Sight target by several inches.

The misses to the torso while aiming at the head on the realistic Front Sight target will occur at shorter ranges when factoring in the ammunition induced error as described above and even shorter ranges due to the shooters imperfect hold in a field position, imperfect sight alignment, imperfect sight picture and imperfect trigger pull.

...........

Where can one find that Front Sight target? I thought for sure Law Enforcement Targets would have it, but I can't seem to find it.

Walmart handily sells Federal XM193 of which I can obtain easily paycheck to paycheck.

As far as iron sights, I mentioned that it is convenient for me to swap to a 1/2 x 1/2 to share the same dope. I can use that rifle for a variety of means, including self defense, but I jumped ship on irons for optics long ago.

As much as you enjoyed shooting holes in my favored stockpile loading of Xm193, you negated my favorite loading in which I use a Hornady HPBT 75 Grain OTM with 24 grains of Varget. This loading is great that it can mimic the trajectory of M193 when utilzied with a 200 yard zero while being more accurate to boot. Having this loading in my repertoire functions as my primary projectile. I evaluated the accuracy benefits of M193 long ago and determined that M193 is a good general purpose round in that it is easily accessible by me and shared among my shooting buddies.

I too concluded that a highly accurate match projectile has the highest probability in intersecting the target. M193 is, in turn, my plinking ammo which just happens to be loaded hot enough to use for self defense though admittedly better options exist.



I agree with you. The limiting factor of the human is the prime element of error. A tired, hungry, injured, or a person under great duress will pull difficult shots with imperfect form and they will be shooting at a target which will almost always present at un-known ranges and for a limited amount of time. I should specify that, again, my irons are fun and all but I have moved to optics for all my serious general purpose rifles and I would advise any shooter to do the same.

My favored rifle sports glass and it would be the rifle I grab for self defense. My primary ammo is 75 grain Hornady OTM in front of Varget for a velocity of 2650 FPS. I reload this loading with convenience in mind. If I wanted it hotter, I could work it up but so far I have been happy with its performance. M193 is stocked deep and cheap as "plinking ammo" but I wouldn't hesitate to use it for self defense if I ran out of my favored loading.    

Tell me this, in your / my scenario where a target is at 300 yards, how much better will someone fare 1) accurately estimating target distance under duress, and 2) apply the correct holdover under duress with a 100-200 yard zero? Which sighting method would incur the least user error, and cause the closest impact to the target whereby secondary projectiles may impede the performance of our assailant?  

Ergo, a rifle firing match ammo from a accurate barrel at the highest velocity attainable will minimize the function of error pertaining to the rifle insomuch as to give the shooter a higher likelihood that he / she may hit a target that presents at unkown distance. As useful as the FBI cadaver study target is, the multiple presentations of a assailant in this hypothetical scenario should be considered as well.  

So what is the problem with using maximum point blank range with the above criteria met (match ammo, optic, quality (accurate) rifle)?  How do traditional sighting methods based on convenience of established range distances improve the hit probability on your FBI target for example? After all traditional sighting methods are based on convenience and are not target defined.  If MPBR of a 6 inch diameter surface is too big for your tastes, you can reduce the MPBR a few yards and go with a 5 inch diameter circle. MPBR would still be the method of sighting that gives you the best chance to hit a target of a defined size.

Luckily we can define our average size targets based on human anatomy.

Since human error includes range estimation, I hope that by utilizing MPBR and a high quality rifle and match ammo, that I am minimizing some of the influence of ballistics poor cartridges and my own failure at range estimation. If we are ever at a point where we are tired, sweaty, beat down, and being shot at... then I hope that by studying my rifle and applying my understanding of my zero that, when I put the crosshair sloppily on the target and mash the trigger... that I have done everything possible to mitigate some of my error and as much rifle error as I could.

And I know from experience how crappy irons are when your tired and dehydrates. Not trying to imply that I am a soldier mind you, but being dehydrated at a High-Power event opened my eyes to just how crappy our eyes can get. I'm glad high power opened up to glass.

Doesn't it all boil down to this: 1) Know the actual avg ES of your ammo/rifle combo, 2) know the external ballistics of the said ammo/rilfe combo for appropriate hold over at varying distances and what is really possible shooting at extended ranges and 3) practice at realistic distances with targets that present a more challenging profile?

Isn't that the gist of it? Or am I missing something?

When I attending a rifle class at CSAT (taught by Paul Howe) he advocated for a 100 yard zero, but stated that if the students used something else and got good hits that he didn't care what the students used. I used a 50 yard zero and had no issues. We were required to do head shots as we closed the distance a little from 100 yards, but didn't shoot at targets wherein only a portion of the target was presented. We only did that with pistols, but a much closer ranges.

Of course the above was just Tac Rifle/Pistol 1 and focusing more on the basics, so, things were undoubtedly more simplified than what would be presented at an advanced course. Plus, this sure wasn't a precision rifle course.

There are certainly more ways than one to skin a cat. Sure I wouldn't hesitate to say that a man who knows his dope and gun is dangerous regardless of what method he uses.

I have been trying to take a zero to ( for me ) the next logical conclusion. I have had great experiences with irons, red dots, and optics at a variety of carbine matches and high power matches with traditional 50-200 yard zero. I had fun with 400 yard movers scoring among the top three shooters using only a red dot at NHRPC one "clinic" we did. I knew my dope and its not hard if you knew that dope. It was a hold above and to the leading corner of our 11 inch wide target (since movers are logically moving with their shoulder to you they were not a full b27 doing the crab walk Molon, just thought you should know) Even did that one with M193.




So yea, train hard at a method and you will get great, regardless of the idiosyncrasies of the methodology which me and Molon will no doubt continue to debate. Until my wife attacks me for doing this all night.

this makes a huge amount of sense to me

thank you

Tag

Thanks, Molon!

MEGA Thanks, Molon!!!

...it now all becomes clear...,

Very useful info, thanks   R.M.

De nada.  

...

Thank you Molon...!!!

Thanks for this very useful information.  I appreciate all you people

What an absolute epic post. Thank you so much the time and effort to present this info to us.

De nada.  


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