AR 15 Ballistics Thread
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This video clip by Travis Haley explains the same thing. My work rifle has a 50 m zero.
My personal rifle is an Armalite with 16" barrel and a ACOG TA01 (4x with BDC). Bear in mind ballistics vary greatly with bullet weight and muzzle velocity. My reloads are 55 gr. Out to 300 m my reloads are very compatible with the BDC reticule. I had the opportunity to use my Armalite at 600 m and found in order to hit a human silhouette I had to use the 800 m mark.
Travis says it quite well. Different zeros apply to different needs. For me in an urban setting and my needs, the 50 m zero ensures that I am +/- 2 inches out to 250 m. For others the 100 m or even 300 m is more applicable.
My personal rifle is an Armalite with 16" barrel and a ACOG TA01 (4x with BDC). Bear in mind ballistics vary greatly with bullet weight and muzzle velocity. My reloads are 55 gr. Out to 300 m my reloads are very compatible with the BDC reticule. I had the opportunity to use my Armalite at 600 m and found in order to hit a human silhouette I had to use the 800 m mark.
Travis says it quite well. Different zeros apply to different needs. For me in an urban setting and my needs, the 50 m zero ensures that I am +/- 2 inches out to 250 m. For others the 100 m or even 300 m is more applicable.
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- Location
- chilliwack BC.
homer76, how do you find the 50m zero at close range? I know its gonna be off, so do you just compensate due to experience or do you have some fancy equipment?
We were just issued Aimpoint Micro T-1's so the majority of the rounds put through my duty rifle are with irons. I currently have 6000 .223 rounds and easily the same amount of .22 LR (with conversion kit) through my C-8. I find for closer distances (less than 10 m) I really need to account for height of the sight over bore and aim about 2 inches high. I just compensate due to experience. I like using .22 LR for really close in difference because it is cheaper and I find there is no real difference in point of aim/point of impact out to 10 m other that it doesn't group as tightly.
If I recall a few years ago a member of LAPD SWAT accidentally killed a hostage when he forgot about offset.
In a law enforcement urban setting I like the idea of putting the red dot on my target and being +/- 2" out to 250 m. Unless it's a hostage rescue shot just aim and shoot (assuming I will have the entire chest to shoot at).
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I have Adaptive Carbine, Adaptive Handgun, and Adaptive Kalash by Travis Haley. I actually like them better than the Magpul videos. In adaptive Kalash he gets consistent hits with an AK at 500 m on a chest sized steel plate (iron sights and Aimpoint Micro).
Gunnerlove
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- Vancouver Island
My 10m zero is also my 700m zero.
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This post was written by Arfcom user Sylvan, who is an officer in the Army and has extensive experience in the sandbox. First is an article on combat marksmanship which gives the reason for his choice of zero - an opinion that a lot of serious shooters share.
Combat Marksmanship
This isn't an expert dissertation. I'm just a joe. There is a lot of debate on what zero should be used for combat and there are pros and cons for each. I will state my opinion and should you disagree, I won't think you an idiot. I merely ask for your reasoning so we can further the discussion and your experience either shooting people or being shot at. First off, some ground rules for the discussion.
You will miss the enemy in combat 90%. This doesn't mean you are going to miss your target. Your target may not be the enemy. It may merely be where you THINK the enemy MAY be. And that's OK.
You will not see who is shooting at you 90% of the time. They will not see you 90% of the time they are shooting at you. Funny how that works.
Bullets that don't hit are still useful. Some misses are better than others (more on this later)
Your first priority in combat is to stay alive and functioning (in that order) (This is also your enemy's first priority.) The best way to do that is to kill your enemy. But that isn't the only way.
Stopping your enemy is done a couple different ways. 1. CNS shot. 2. Bleed out. 3. He quits. Only one of these can you count on instantly. Number 2 becomes easier the more times you shoot him. 10 holes bleed out faster than 2 holes. You can't count on #3, but this is the option that is most common. Doing options 1 and 2 on his friends helps option 3.
Lethal combat distances are generally within 50M. Most everything else is a battle for fire superiority to allow maneuver to the lethal distances. You can argue this, but history and my personal experience supports my opinion.
Combat Zero
The common zero ranges for the M4/M16 family are 25M (Iron) 36M (ACOG) 50M and 100M
The 25M gives you a zero that roughly matches a 300M zero based upon trajectory and bore access. This is the standard zero and allows the firer to hit a man sized target when aimed center of mass from between 25M out to 350M. Everything between 25M and 300M the round will go high over the point of aim.
The 36M is specifically designed for the RCO TA 31F ACOG. This optic, properly used, gives you an accurate 100M 200M 300M aim point assuming your range estimating is correct.
The 50M zero is designed to match a 200M zero. It has the smallest amount of overall deviation in trajectory from 25M to 300M. You will be high between 50M and 200M and low past 200M.
The 100M zero gives you a limited zero everything within 100M and beyond the bullet will impact low.
Combat shooting is not MOA of anything. Generally speaking the rifle and bullet combination will yield a 2-3 MOA assuming the operator can shoot. Many can't. And that's OK, too.
Assuming that you are going to miss the enemy 90% of the time, how do you make the most of those misses?
In my opinion (and in the opinion of many others) the 100M zero is the best zero for a combat rifle. For me it comes down to: if you are going to miss, a low miss is infinitely superior to a high miss.
Missing low will often give you a visual impact allowing you to adjust fire. A high miss gives you nothing in feedback. (Indeed, you may have hit the target and not even known it)
Missing low will often cause bullet fragmentation, a skip or richochet, and/or create secondary projectiles of rocks, twigs and debris. Even a cloud of dust can temporarily blind an opponent. These are all good ways to ensuring your 1st priority, staying alive.
Shooting high is a common mistake at night and when panicked. A zero which cheats to low compensates for this fact.
A COM miss high may or may not hit the head. A COM miss low is more likely to hit the hips or legs. You got 18" of play going high. You have 40" (or so) of play going low. A hit to the pinky toe is better than 1cm over the head.
Psychologically, I believe, the impact of bullets in front of me is a much bigger skull #### than the snap and hiss of bullets going over my head. I don't know if it is true for everyone, but its true for me.
The Rhodesians and others developed drills around these assumptions. In what is known as the Drake Drill or cover shoot, the Rhodesians responded by returning fire to the left and slightly below all SUSPECTED enemy positions. This drill was designed to gain fire superiority to allow maneuver. It often had the secondary benefit of actually killing or wounding the enemy. The key point to this drill is NOT to just fire your bullets in the general direction of the enemy. It was to quickly identify probable enemy positions and engage to the left and low of possible cover (assumption being the enemy is most often right handed). The first two magazines of FAL were to be expended quickly in this manner and then to retain the remaining ammunition for aimed fire as they closed with the enemy. Doing this same drill with 2-3 magazines of M4/M16 would probably be a good use of your basic load.
Combat Marksmanship
This isn't an expert dissertation. I'm just a joe. There is a lot of debate on what zero should be used for combat and there are pros and cons for each. I will state my opinion and should you disagree, I won't think you an idiot. I merely ask for your reasoning so we can further the discussion and your experience either shooting people or being shot at. First off, some ground rules for the discussion.
You will miss the enemy in combat 90%. This doesn't mean you are going to miss your target. Your target may not be the enemy. It may merely be where you THINK the enemy MAY be. And that's OK.
You will not see who is shooting at you 90% of the time. They will not see you 90% of the time they are shooting at you. Funny how that works.
Bullets that don't hit are still useful. Some misses are better than others (more on this later)
Your first priority in combat is to stay alive and functioning (in that order) (This is also your enemy's first priority.) The best way to do that is to kill your enemy. But that isn't the only way.
Stopping your enemy is done a couple different ways. 1. CNS shot. 2. Bleed out. 3. He quits. Only one of these can you count on instantly. Number 2 becomes easier the more times you shoot him. 10 holes bleed out faster than 2 holes. You can't count on #3, but this is the option that is most common. Doing options 1 and 2 on his friends helps option 3.
Lethal combat distances are generally within 50M. Most everything else is a battle for fire superiority to allow maneuver to the lethal distances. You can argue this, but history and my personal experience supports my opinion.
Combat Zero
The common zero ranges for the M4/M16 family are 25M (Iron) 36M (ACOG) 50M and 100M
The 25M gives you a zero that roughly matches a 300M zero based upon trajectory and bore access. This is the standard zero and allows the firer to hit a man sized target when aimed center of mass from between 25M out to 350M. Everything between 25M and 300M the round will go high over the point of aim.
The 36M is specifically designed for the RCO TA 31F ACOG. This optic, properly used, gives you an accurate 100M 200M 300M aim point assuming your range estimating is correct.
The 50M zero is designed to match a 200M zero. It has the smallest amount of overall deviation in trajectory from 25M to 300M. You will be high between 50M and 200M and low past 200M.
The 100M zero gives you a limited zero everything within 100M and beyond the bullet will impact low.
Combat shooting is not MOA of anything. Generally speaking the rifle and bullet combination will yield a 2-3 MOA assuming the operator can shoot. Many can't. And that's OK, too.
Assuming that you are going to miss the enemy 90% of the time, how do you make the most of those misses?
In my opinion (and in the opinion of many others) the 100M zero is the best zero for a combat rifle. For me it comes down to: if you are going to miss, a low miss is infinitely superior to a high miss.
Missing low will often give you a visual impact allowing you to adjust fire. A high miss gives you nothing in feedback. (Indeed, you may have hit the target and not even known it)
Missing low will often cause bullet fragmentation, a skip or richochet, and/or create secondary projectiles of rocks, twigs and debris. Even a cloud of dust can temporarily blind an opponent. These are all good ways to ensuring your 1st priority, staying alive.
Shooting high is a common mistake at night and when panicked. A zero which cheats to low compensates for this fact.
A COM miss high may or may not hit the head. A COM miss low is more likely to hit the hips or legs. You got 18" of play going high. You have 40" (or so) of play going low. A hit to the pinky toe is better than 1cm over the head.
Psychologically, I believe, the impact of bullets in front of me is a much bigger skull #### than the snap and hiss of bullets going over my head. I don't know if it is true for everyone, but its true for me.
The Rhodesians and others developed drills around these assumptions. In what is known as the Drake Drill or cover shoot, the Rhodesians responded by returning fire to the left and slightly below all SUSPECTED enemy positions. This drill was designed to gain fire superiority to allow maneuver. It often had the secondary benefit of actually killing or wounding the enemy. The key point to this drill is NOT to just fire your bullets in the general direction of the enemy. It was to quickly identify probable enemy positions and engage to the left and low of possible cover (assumption being the enemy is most often right handed). The first two magazines of FAL were to be expended quickly in this manner and then to retain the remaining ammunition for aimed fire as they closed with the enemy. Doing this same drill with 2-3 magazines of M4/M16 would probably be a good use of your basic load.
From: http://www.m4carbine.net/showthread.php?t=63618
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 upwards towards 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.
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 or 215 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 more 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.
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 upwards towards 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.
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 or 215 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 more 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.
