View Full Version : AR sighting in question

23 Blast
03-23-2011, 5:43 PM
Hi all,

I just spent a rather frustrating day at the range with my latest acquisitions, a Mini 14 and a AR-15. The AR is my first AR rifle of any kind. It is a 20" heavy barrel upper (Armalite upper) coupled with a Stag lower - it looks for all the world like a M16A2, complete with the A2 rear sight assembly.

Anyway, I managed to get the Mini 14 sighted in, but the AR just continually frustrated me.

Am I supposed to use the 0-2 aperture to sight in? Or the much smaller (and I'm assuming, therefore much more precise) regular aperture? I noticed that when you flip between the two apertures, it sure looks like the center of each aperture is off from each other by a milimeter or so - they're not lined up on the same vertical axis! So at first I was trying to sight in with the large 0-2 aperture, then grew frustrated because I couldn't even track where the heck I was at all: I wasn't even on the paper, and given that the ground was damp and the day overcast, i couldn't even use the approximation of using a spot on the berm and watching for the splash.

03-23-2011, 6:09 PM
Small hole. Make sure(if its the carry handle sight) the knob is on the "2/3"(or 3/2 can't remember what the number is) notch and not on the "z" notch. Battle sight zero first. Make sure the line on the sight hole is on the center line on the carry handle. Make sure the front sight post base is flush with the top of the sight block. Should put you on paper. At least at 25 meters.(For a 300 yard zero with 62 grain m855) Telling you what we use on the army. Then once that's good move out farther and fine tune it.

03-23-2011, 6:42 PM
Small hole. Make sure(if its the carry handle sight) the knob is on the "2/3"(or 3/2 can't remember what the number is) notch and not on the "z" notch. Battle sight zero first. Make sure the line on the sight hole is on the center line on the carry handle. Make sure the front sight post base is flush with the top of the sight block. Should put you on paper. At least at 25 meters.(For a 300 yard zero with 62 grain m855) Telling you what we use on the army. Then once that's good move out farther and fine tune it.

^^^ What this guy said.

Just don't ever use the large 0-2 aperture. Seriously.

03-23-2011, 6:46 PM
This might be helpful:


The IBZ is probably the way to go for most people unless you have specific needs.

03-23-2011, 7:34 PM
Here's another one, same as above but has more questions and answer post which might give you a better picture.


03-23-2011, 8:20 PM
I'm sorry, I figured out what they were saying. based on the max distance the BUIS MOA is good for. .

Always use the small hole, the large hole is for fast moving snap shots close range.

I dont know what you mean by A2 either? an A2 upper or you have a BUIS A2 type...Spin the hood all the way up, look at the threads. Thick threads are for the 20" A2, Thin threads all the way to the hood are National Match threads, if you can not see any threads you have a A4 hood. Click the elevation back down till it stops. look on the left side an A2 will say 8/3 a Carbine needs to say 6/3. Turn it to "4" counting the clicks... 3 clicks is 1/2 MOA per click. NM and A4 should have 6 clicks for 1/4 MOA per turn. a NM hood (threads all the way to the top of the hood) are spaced closer to 1/3 MOA I am told... never confirmed.

A 25 meter zero puts a round +10 inches above Point of Aim 210 yards away. That is the top of the arc. On the down slope it zeros again at 350 yards. And a target 400 yards away, the round will strike 5 inches low. The best thing with the 25 yards zero is a 2MOA dot is 4" across at 200 yards. so you know your rounds will strike just above the dot and if a target is 400 yards away the rounds will strike on the bottom of the dot (@ 400 yards a 2MOA dot covers 8 inches").

A 50 yard zero has a cross zero of 210 yards. If you use the IBZ directions you really need to do a 50 yard zero so you can adjust the elevation wheel and the numbers on the side will approximately be the proper range. I would NOT use a IBZ with a 20" NM or 20" A2 8/3. There is no need. Many people like it, but if you are shooting NM, you dont want a 50 yard zero. At least i wouldnt think you would.

I dont know who made this chart I stole it since it was better than the one in my manuals and puts all 4 zeros on one chart.

Notice on a 50 yard zero you must spin the elevation wheel or your target will not be visible to you in your sight picture even at 400 yards, while a 25 meter zero with a 20" you are good till 600 yards at 15 inches low.

Here is the IBZ, if you are going to use it, follow it to the letter.

An Improved Battlesight Zero
for the M4 Carbine and M16A2 Rifle
1. Current Army/Marine Corps battlesight zero and it's procedures are well described in TM9-1005-319-10, the M16/M4 operator's manual. A recent copy of this manual is available for download at the Manual Depot. Procedures in the manual will not be repeated here.

2. The current 300 meter battlesight zero is a function of the sights on the rifle and I personally find it shoots too high for the vast majority of combat targets, including the Army's qualification ranges. The procedure listed here takes better advantage of the flat trajectory of these rifles as well as the use of civilian ranges, which are seldom surveyed in meters.

3. When zeroed at 200 meters, a distance twice that of normal combat engagements, these rifles have a very flat trajectory that is less then 2" from line of sight at all intermediate distances; a distance that's smaller than the normal dispersion of arsenal or factory loaded ammunition. This tiny trajectory arc allows very precise shooting out to 250 meters where the bullet is only 2" below line of sight.

4. A 200 meter zero has the happy coincidence of an initial trajectory cross-over at 50 yards, a distance available on almost all civilian ranges including many indoor ranges. This makes it easy to achieve a 200 meter battlesight zero without recourse to surveying your own range. If 200 meters is available you can fine-tune the zero at the real distance. And should when you get the chance.

5. The lowest sight setting, however, on these sights is 300 meters so the sight needs to be modified to preserve the markings on the sight (despite the fact that no one ever sets a range on these in the real world other than a USMC range). The sight needs to be set to bottom out at 8/3 -2 clicks. This will be the new 200-meter setting.
1. Flip the rear sight back to the unmarked aperture. This will reveal a hole in the top of the handle.
2. Rotate the sight wheel all the way down. Will probably be exactly at 8/3 (6/3). Don't force it down.
3. Using a 1/16" Allen wrench loosen the screw (under the revealed hole) in the sight wheel 3 full turns. Leave the wrench in the screw.
4. Rotate the bottom half of the sight wheel two clicks clockwise. This will raise the sight body if you look at it while you're turning it.
5. Tighten the Allen screw, remove the wrench, and confirm the sight bottoms out at 2 clicks BELOW 8/3. If not repeat the procedure until it's right.

6. Battlesight the rifle per the -10 with the following exceptions:
1. Sight should be at 8/3 -2 clicks, that is, all the way down, not up a click. Please note removable handle sights are marked 6/3 (rather than 8/3); also some are in ‘half-clicks’ as well. There should be 3 clicks between 3 and 4 on the knob. If there are 6 clicks then the sight needs to be set at –4 clicks (instead of –2).
2. Small aperture, nose to firing handle weld.
3. Distance is 50 yards.
4. Point of aim should be point of impact of bullet.

7. Remember you're adjusting the FRONT SIGHT for elevation, not the rear, and that each click is about 1/2" (actually a little more) at 50 yards. You won't get it closer than that. Don't frustrate yourself trying.

8. You're done. Leave the sight in this position for 99% of your shooting.

9. If you have to shoot targets you KNOW are 300 meters away or more, just click to the right number on the sight.

10. If you're patrolling, set the sight to 8/3 and snap the aperture forward to 0-2. This will provide the same trajectory as above but with a larger, easier to see thru rear sight. Use this setting if you also have the M68 mounted as it's quicker to transition to if the sight fails. [Editor's Note - there is some variance with the offset of the A2 aperture - they SHOULD be a 2 click difference - however some manufactures produce them with larger offsets. Setting the sight to 3 then flipping to 0-2 might now work for your AR. Check it at the range, you want the group to be centered at 50y, you might need to set the sight at 3 +2 or even 4 to get the large aperture to be correct]

11. If you have an M68 CCO (Aimpoint CompM-XD) optical sight battlesight it to 50/200 as well. You can shoot to 300 meters by merely holding "over a dot."

12. This battlesight zero is valid to 300 meters for both the M16A2 and M4 Carbines and their AR15 sisters. It's valid with any ammunition that approaches the specs for M193 (55gr) or M855 (62g) Ball ammunition. It works for both rifles and carbines due to the offsetting influence of higher muzzle velocity in the rifle being offset by the longer sight radius that moves bullet strike less per click. This is battlesight, not X-ring shooting!

13. This battlesight zero does not reflect the doctrine of the US Armed Forces, however, it reflects the personal use of these weapons in combat and in training for over 34 years.

14. Comments to: Lt. Colonel Chuck Santose (santose@compuserve.com).

Original document: 990104
Copyright 1999, 2000. All rights reserved.

Follow this to the LETTER..

23 Blast
03-23-2011, 9:09 PM
Thanks all for the responses. dieselpower, my rifle's upper has the carry handle-mounted rear sight. The carry handle is non-detachable. Here's a pic of my gun, if it helps, but the pictures included in the instructions for the RIBZ look a lot like what I have. I have that setting that says 8/3, but I thought that that was the minimum setting, and you shouldn't go lower than that. When I did screw down the sight below that 8/3 setting, it seemed to torque the sight sideways a bit, which obiously screws up the alignment of the sights.


03-23-2011, 9:18 PM
What distance are you shooting at? You should start close 10-15yds and see where it is printing. Can't start at 50-100yds and expect the gun to print, especially with open sights.

23 Blast
03-23-2011, 9:37 PM
I was at Burro Canyon: although it was Wednesday and therefore we are our own range officers, IIRC the minimum target range is 50 yards (ie they frown on folks bringing their targets in close)

besides, 50 meters SHOULD allow a rifle to at least be on paper, but I suspect I was trying too many rounds with the rear sight elevation screwed down so low that it was torqued sideways. Just not a fun morning all around :'(

03-23-2011, 9:49 PM
Couple things... Since you are sighting in at a 50 yard range, use the IBZ I printed. Even though its a NM 20", since that is what the range has, use it. Check your clicks from 3 to 4 and do the Allen wrench thing, - 2 for 3 clicks between and - 4 clicks for 6 clicks between. a NM has 6 clicks, but make sure. You could have a Standard A2 with 1/2MOA clicks which will only be 3 clicks. COUNT THEM.

You have an Armilite Upper, its a little different then a AR15A2. Its made for extreme accuracy, but you need to understand the front sight. Here is a supplement from Armalite...If you have this front post make sure it is centered and not off one way or the other. If you bought this used, it is possible someone goofed with it.

ZEROING THE FRONT SIGHT FOR WINDAGE: Normal manufacturing tolerances
can result in the rear sight being off-center when the rifle is zeroed. ArmaLite’s
exclusive screw-clamping gas blocks (T and A4 models) and front sight bases (AR-10
and M15-A2 models and AR-180B) allow the owner to zero the front sight for windage
with the rear sight perfectly centered. This is especially important for competitive
shooters, who generally wish to have equal windage adjustments available to both the left
and right.
To zero the front sight, put the rear sight aperture in the center of the rear sight base. Fire
a three-shot group to see where the rifle is shooting, then adjust the front sight based on
the horizontal location of the shot group. To adjust the next shot group to the left, loosen
the clamping screws and shift the front sight to the right slightly. Very little movement
is needed. To shift the group to the right, move the sight slightly to the left. The sight
should be easy to move by hand or with very light taps of a leather or nylon mallet.
Tighten the base and try again.
If the sight is too tight to shift easily, you may loosen the bottom of the sight base.
Remove one or both of the screws, screw it (or the m) into the opposite side and tighten
very slightly against a coin or blade slipped into the split at the bottom of the sight base.
The sides will spread apart easily.

what happens with many standard rifles is the rear sight needs to start a few clicks left or right of center to be zero. This is bad for guys shooting 500 yards since they may need more clicks left. If you already start over to the left, it gives you less adjustment. Armalite fixed this by building a front sight post you can adjust to the left or right too. So you do not set your left right zero by moving the rear windage adjustment...you do that by setting the front post left or right, then locking it down. now your rear BUIS is starting from center.

23 Blast
03-24-2011, 12:32 AM
Another question:

the IBZ and the RIBZ make mention that, when your (unmodified) rear sight is dialed all the way down, it should be at the 8/3 setting, and you shouldn't be able to force it lower. Well, my gun was bought used, and I know that when I got it, I could certainly screw down the rear sight beyond (lower) than the "minimum" 8/3 setting. Does this indicate that a previous owner might already have performed the IBZ or RIBZ?

Should I try to return the rear sight to it's factory settings, and then try to "re-do" the IBZ or RIBZ?