ar-15 zeros and trajectories

7/27/2019 AR-15 Zeros and Trajectories

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AR-15 Zeros and Trajectories

The 100 yard zero with a .223/5.56mm AR-15 carbine is a unique trajectory in thatthe 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”; afraction of the diameter of the bullet itself.)

For all other zeroing schemes, there are going to be two points were the bullet

crosses the line of sight; the near-zero and the far-zero. For the near-zero, the bullet

will cross the line of sight while traveling 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 50yard/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.

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



Courtesy of zrxc77

M855 25 yard zero



M855 25 meter zero

M855 25 meter zero versus 300 meter zero



M855 36 yard vs 100 yard zero

M855 and M193 25 meter zero



M855 and M193 50 yard zero from 16” barrel

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



100 yard zero

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



M855 300 meter zero

M855 200 meter vs 300 meter zeros



M855 36 yard vs 50 yard zeros

ar-15 zeros and trajectories

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