Have some AR-15 sighting questions

[colostomyclown]

So I just bought a Rock River m4gery, flat top with fixed trianle front sight and no rear sight. I bought a REAR Magpul flip up BUIS to work with the front fixed sight and plan on co witnessing the irons with a Burris Fastfire. Here's the problem:


The MAGPUL rear doesn't have an elevation adjustment, just windage (side to side). Does this mean I have to get the bullet shooting straight with the rear sight first then adjust the elevation with the front sight? Do I need to buy the magpul front BUIS to use the rear? What's the deal? From what I understand the front post isn't touched all that often and is more or less where it needs to be and the adjustments are to be made to the rear.

Please help, especially if you run these magpul sights...

[Willie Lowman]

Step one: shoot at paper to see Point Of Impact vs Point Of Aim.

Step two: if the POI needs to come up to match with POA you lower the front sight (turn the frond sight clockwise. you can use the tip of a .223 fmj round) if the POI needs to come down you raise the front sight. (turn the front sight counter clockwise)

Step three: once the bullet is striking on the same same (X) axis as the POA adjust the rear sight to the left if the POI needs to go to the left or to the right if the POI needs to go to the right.

????

PROFIT!

[colostomyclown]

thanks! A boresighter wouldn't be a bad idea would it? Might save ammo in the long run?

[Quentin2]

Good info above. I'd also say skip the bore sight. One round from a benchrest will be a better POA/POI indicator anyway.

[TeamSinglestack]

From what I understand the front post isn't touched all that often and is more or less where it needs to be and the adjustments are to be made to the rear.

The addition of an integrated elevation knob on the rear sight of the M16 family is a later development, and was not included in the design of the M16A1 series. This design development allows for making rapid sight adjustments to accommodate targets at ranges beyond 300M, and until this development, shooters would be required to either use a hold, or make elevation adjustments using the front sight, which is a pain in the rear.

Initial zeroing calls for placing the elevation knob in a neutral position, and making all elevation corrections using the front sight post. Once the zero has been achieved, the shooter can then use the elevation knob to make the adjustments needed to engage targets beyond the range of the zero, without having to fiddle with the front sight post.

Since you don't have an elevation knob, you will zero just like any other rifle with simple windage/elevation iron sights. No worries. Engaging targets beyond the range of your zero will require a hold, or front sight adjustments, to bring the strike of your round up and onto your target.

However, unless you are shooting beyond 300M or so, that shouldn't be an issue depending on the zero you use.

[Eghad]

Back in the day we did what we called a mechanical zero. The front sight was turned till it went all the way down and was turned back up to the halfway point. The elevation was turned till it was all the way left or right then turned back halfway. I think most rear sights have two index marks on them now to center the rear sight????

front sight = elevation
rear sight = windage

See if you can google up some military zero targets for your weapon. send three shots downrange and the target will tell you which way to turn the front and rear sights to zero. You might need to know if your sights adjust at 1/4 or 1/2 per turn at 100.

The zero target is set at 25 meters as the usual rounds will hit at 25 meters and 300 meters in the same spot when it comes to the rise and fall of the round.

[alloy]

See if you can google up some military zero targets for your weapon
http://ohmr.ohio.gov/forms/ohmr2444-b.pdf

set page scaling to none

[scsov509]

The zero target is set at 25 meters as the usual rounds will hit at 25 meters and 300 meters in the same spot when it comes to the rise and fall of the round.

A lot of us are now also using Improved Battle Zero which calls for a 50 meter zero that is also zeroed at 200 meters. That's my preferred zero on my AR's, but you may choose something different. Also, don't know about your RRA, but mine actually came with a manual explaining how to zero an AR-15. It's worht the read if you have it. :cool:

[Rattlehead]

You can also save the $$ on a boresight tool by shotgunning the rifle, popping out the bolt carrier, and placing it in a stable position (if the buttstock's now down at 90 degrees, that makes a pretty good platform ;))

The you can look directly down the bore and align your sights on that - find a target at your desired distance downrange and use that.

It may not be as precise as a laser boresight, but it should put your shot group on the paper.

[Eghad]

The 25M zero had the same point of impact at 300 meters. I used the 25M target to zero my M4 with My EoTech.

The lady at the range was concerned when I showed her the zero target I was going to use. She thought I might miss and hit one of the clips they put on wire to hold targets. I promised her I would not hit a clip at 25M. If I did I would buy her 1000 new clips. lol

On my other M2 style Rifle I have a Leupold 1-5 scope for the .223. On top of that I have a small red dot sight for close up. I used the 25M zero target on those also. The only difference being that to use the the small red dot sight I use the right side of my chin for the stock weld position.