AR-15 iron sight zeroing

[wnycollector]

I decided to pull the scope off my 20" AR and use it on my new Reece build. I picked up a MI fixed rear sight for the 20" to make it a KISS rifle. The MI fixed rear sight uses the A2 aperture w/ A1 windage adjustment, but it's essentially an A1 sight. I read Molon's RBIZ over at AR15. com, but that focuses on the A2 sight, is there a version of the RBIZ for an A1 type sight?

 

[Z-Michigan]

With an A1 rear setup you basically just choose what distance you want to zero at and do it. End of story. I would suggest 50 yards as a good zero for general purpose use with 55 or 62gr military type ammo. Beyond that plug in your load's velocity and drag coefficient into a ballistic computer with different zero distances and see what you like best. Try this:

http://www.handloads.com/calc/index.html

 

[wnycollector]

With an A1 rear setup you basically just choose what distance you want to zero at and do it. End of story. I would suggest 50 yards as a good zero for general purpose use

Perfect. That is what I have been doing with my BUIS, so this is really not any different. It looks like my typical range ammo (BB 55gr FMJBT) will be 1.53" high at 100 yards and dead on at 215 yards w/ a 50 yard zero.

 

[Pingy]

That RBIZ is much too complicated for my tastes. Dug up my old rifle range manual and found the steps for doing a BZO. It's for the M16A2/A4 using iron sights, but since it uses the 300 yard setting it should be usable on any kind of sights if they are the same distance off of the bore centerline. Obviously we were using green tip bullets, forget what they're called but you can probably google it.

The short version is, set up a target at 36 yards and dial your sights in for 300 yards. At 36 yards the bullet will cross your LOS rising, and at 300 yards it will cross your LOS falling. Effectively sighting in your rifle for a 300 yard Zero using only a 36 yard rifle range.

If the rifle is shooting high or low, make the elevation adjustments on the front sight.
Move post clockwise to raise shot group.
Move post counterclockwise to lower shot group.
Windage adjustments are made on the rear sight.

After that whatever you put the sight setting on should be where it shoots. 200 yards 500 yards etc. My A4, which I have the shots marked for in this log book was right on, but my old A2 had to go a click or two up or down at 500 yards to be exact. Hope this helps.

 

[kwelz]

50 yard Zero is best. It ha you on at 50 and 200. And allows for very fast and easy correction at shorter ranges.

 

[Pingy]

50 and 200 huh? Yea, that would be better than 36 and 300 for most things I could think of. So then you'd just put the sights on 200 and shoot at a 50 yard target to get the zero. Easy peasy. Get to know where the bullet is at between 50-200 and 0-50 and you'll be spot on anywhere up to 200.

 

[kwelz]

If you Zero at 50 yards you will need to aim ~2.5 inches high at 5 yards and ~2.5 inches low a 100 Yards. It doesn't get much easier than that.

 

[Quentin]

The RIBZ or earlier IBZ is not complicated and actually is a lot of fun, very flexible. But you need the elevation wheel which an A1-style sight does not have so I agree with others to go with the 50/200 meter zero.

You could buy another rear sight like the LMT or RRA that are basically cut down carry handles and then have the elevation wheel.