How to zero without a rear elevation knob

[Ron Swanson]

I need to zero in my AR-15. It only has iron sights with the rear being the ProMag PM136 flip-up sight.



When I look at the instructions to zero in at 25-yards it says to set the rear sight to 8/3, but this sight doesn't have an elevation knob, only a windage dial.

Ideally, I'd like to zero it in at 50-yards. Is the lack of this feature imperative to properly zeroing it in?

[Merc1138]

I need to zero in my AR-15. It only has iron sights with the rear being the ProMag PM136 flip-up sight.



When I look at the instructions to zero in at 25-yards it says to set the rear sight to 8/3, but this sight doesn't have an elevation knob, only a windage dial.

Ideally, I'd like to zero it in at 50-yards. Is the lack of this feature imperative to properly zeroing it in?

So adjust your zero using your front sight.

[tnlrat37]

^^^what he said, your front sight post should move up or down with a tool or even the tip of a 5.56 round. 8/3 is elevation on m16a2 rear sights for either 300 or 800 meters depending on if you rotate it 360 degrees if I remember right

[bombadillo]

http://www.midwayusa.com/product/112543/promag-front-and-rear-sight-adjustment-tool-a1-ar-15

[teflondog]

I use spent 5.56 brass to adjust the front sight.

[Ron Swanson]

I understand I can adjust the front sight. My concern is to zero it at 25-yards I'm supposed to adjust the rear to 8/3. When I move it back a click I am then zeroed for 300-yards too. I suppose, I will only be able to zero it at one distance.

[ke6guj]

your sights don't have an 8/3, so you can't use those directions. you have Backup Iron sights which are designed for "backup" "close enough" work. those sights that have the 8/3 knob are designed to be used a primary sights and are adjustable for various ranges. with BUIS, you just sigth them for something like 100yards and forget about them unless you need them. at that point, you just hold high if you have to shoot farther.

[mark501w]

Back to the 60's elevation of the front blade!

[Ron Swanson]

your sights don't have an 8/3, so you can't use those directions. you have Backup Iron sights which are designed for "backup" "close enough" work. those sights that have the 8/3 knob are designed to be used a primary sights and are adjustable for various ranges. with BUIS, you just sigth them for something like 100yards and forget about them unless you need them. at that point, you just hold high if you have to shoot farther.

Ah, I didn't know that, makes perfect sense now. Thanks!

[Munny$hot]

Zero at 50/200 like you mentioned and you'll either be 1 1/2" low @ 25m or @ 1 1/2" high ar 100

[JohnFLand]

If you think about bullet arcs, you always have *2* zero points, the close one being on the upward slope and the far one being on the downward slope (unless you somehow zero on the tangent). Where those two zero points are depends mostly on the ballistics of your ammo.