Hey everyone, as you may have guessed I'm new at this and just finished putting together a DPMS AP4 carbine with plenty of goodies. My problem though, I sighted in the EOTech 512 holographic sight nice and easy. But when I use my Troy rear BUIS with the front sight post my shots are high and to the right. Now I am not familiar at all with AR-15 iron sights. Only ever shot a glock and shotgun. To get my shots where they should be I had to lower the front sight post pretty far and slide the rear peep sight all the way to the left. What am I doing wrong? Or is this typical? Please feel free to pick on me of course!

So it's hitting point of aim right?

You have have done it right, depending on your eyes.
All my rear irons need to be pretty left of center for windage.
That's just the way my eyes are.

Another thing that will change windage and elevation is not looking through the center of the rear aprature.
Keep your head as straight up as possible and don't lean your head over the stock.
I used to lean over the stock when I shot off the bench.  Now I try to bring the stock to my face,
rather than lean my head on the stock.

ETA  Welcome to the craziness.  You'll find some real experts here.  
You'll also find people who know everything about everything, but that's part of the fun.

It depends on your range to target.  if you have zerod your optic at a certain range, for a certain ammo, when those conditions change, so will your POI. bullets will go right due to the spin. the POI could be high due to your range.  what method did you use to zero your BUIS and what range are you shooting at, what ammo? where is your front sight post.  I have only had 1 cup of coffee so bear with me if i missed something in your OP.

google "improved battle zero".  first set that up on your BUIS then if you need big time adjustments there could be a problem with your FSB or rifle.

It should be noted the the mechanical windage zero of your rear sight (i.e., perfectly centered) is not necessarily the rifle's windage zero.  Most rifles will require several clicks left or right to get them zeroed.

Now, if you're at max or near-max of adjustment, you might have a problem.  

The same is true of your front sight.  The sight post won't necessarily be zeroed at the true middle of its vertical travel.

I had a similar issue where my shots were hitting about 8 inches right of the target, and I too had to move the peep sight all the way to the left. It turned out the front sight post was canted just slightly, but that sort of thing throws you way off at distance. Take your eotech and peep sight off the rifle and look very closely at the front sight post.

First determine if you're planning on utilizing the center mass (point of aim), 6 o'clock hold or both? This illustrates open pistol sights but, the concept of the front sight is the same for peep sights - just don't pay attention to the ears of the front sight - only the post.


Second, your eye should naturally focus center in the peep sight, from here focus on the tip of the post - not the target (the target and peep should be blurry, the only thing in focus is the front sight post).



Sakic #19

Heres A good target I found for zeroing  your irons for a center of mass POA

Thanks everyone for the information and quick responses. I took it out again today using cheap PMC 55 grain FMJ boat tail ammo and was blown away by the accuracy of the eotech, so much that I completely forgot to resolve my issue with the iron sights hahaha. I will head to the range again in a few days and take another whack at it. The illustrations were especially helpful because I was using just above the center of the post as the point of aim, like the big white dot on my glock post. I will update later if I finally got it right. Thanks again all! Oh and is it okay if I post pics in here to show everyone my build or is there a special place for that?

Check out the "Build it yourself" section if you want to make a detailed post.

But I don't think anyone would mind a pic or two.