I got a new AR for christmas and went to zero it today. I set my rear site one click up from the 8/3 300m mark and had been moving my front site post down to raise my shots. I was using 25m Military zero targets and was able to get within about two inches of the bottom of the target before the front site post wouldn't lower any more. when I changed from "lolipopping" my site picture to covering my taget with the front post I was able to get within about 1.5 inches of that little guy but still not on the black. This has never happened to me before on any of my AR's and I always have more down movement in the front site posts but not on this one. I really don't want to have to have to cover the target with the front post if I don't have too. Any help, suggestions? Thanks. Sorry for the long post.

It might be helpful to post the brand and type of rifle as not all front sights are the same.

First off, the rear sight has a allen head screw that is accessible threw the front hole in the housing to allow you to change the knob settings to zero the rear sight.

Reset the front post to be level with the front sight housing, then try to zero the rifle using the rear sight(raising it).  Once you have gotten close, tighten the rear sight knob to 3/8 using the set screw, then fine tune the front post to get you on zero. The front post will allow you to fine tune the elevation, verses the mass moment of POI that the rear has to offer.  And, depending on your front sight post, you can file the post down to raise the POI. On some rifles with Service sights, this allow the POI to be moved in less that 1/8", if needed.

Also, until you move your distance out to at least 100 yards, don't start marking you sight for the zero setting. Your short zero will change slightly when the distance is stretched.
And, if you start changing ammo(type/brands),the POI will change too.

P.S. Don't worry about writing novels. The more information that you give, the sooner that we can get to the correct answer.

It's a Bushmaster 20" HBAR. Thanks for the Info Dano523, Ill try that when I get time to go to the range. It would be cool to have a range in my basement so I didn't have to wait to try that out, lol. And no more range rules either, lol. Thanks again.

My DCM Bushmaster came with a manual which detailed the sighting procedure and also shows the little allen screw below the front sight post. I had to put my front post below flush to keep the rear sight low to leave elevation. It only took about 1 turn below flush to raise me about 5".

Kevinj54,
Chances are that your rear sight does not have the range settings, but a double sided elevation knob that can be flipped to change the MOA for adjustment.

His rifle is a stock rifle with no front sight tighten screw(only detent plunger), and his rear sight is a standard sight with range markings.
The point he missed when zeroing is that his rear elevation knob settings can be changed by a allen screw in the top of the knob and are reached threw the hole in the front/top of the housing.

This allows for the back sight to be set close to zero, then the front post moved a few clicks to fine tune. On his sights, the range settings are marked(factory match to Nato ammo).

Your rear sight on the other hand, should be able to adjust the POI my as little as 1/4"MOA, and marked for different zero's(match loads) with the use of a sharpie.

Your sights and Wipeouts are not the same design.  
And, the fact that he may have a front post that is too tall, can still be corrected with the rear sight.

thanks everyone for your great replys. The allan screw that you are talking about is the one in the top of the rear sight looking down from above the rifle, right behind the sight aperature, right?

That's the one.

Kevin was talking about a set screw that is used on the front sight to keep it from canting , once the front post is set.
Yours will not have the front set screw, so don't bother looking for it

Dano

My rear sight is all marked out and has the adjustable scale by small allen from the top but to keep the rear sight low and minimize the slop when set for long yardage I had to put the front below flush rather than file it off. I may file it when I am satisfied with my settings so the front sight can be flush for the sake of appearance. Is it normal for the standard front sight to stop at flush as Wipeout is saying. I think my front sight standard with the set screw added ??

Head on over to this webpage:
The Maryland AR15 Shooters Site

This is LTC (Ret) Chuck Santose's Improved Battle Sight Zero Instructions.
Chuck Santose knows his shit!
I use it on all of my AR15's and it is great.
After you set it up using his method you can then set up your rifle to suit you.
I know the number of clicks it takes to get me to zero for 25, 50, 100 and 200 yards.
It works!

[url]http://groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw[/url]

Improved Battlesight Zero by LTC Chuck Santose.  A great all purpose zero for all rifles/carbines (no matter the iron sight type); and you zero in yards (50) instead of meters.  It keeps the bullet within 2" of the point of aim from 8M to 220M (very flat trajectory).  Also perfect for carbines with A1 sights; and ARs having a 'Red Dot' type sight inline with their iron sighs [on a flattop or in front of the carry handle].