AR-15 Sight-In ????

[Aguila Blanca]

I can't believe this hasn't been discussed, but after perusing more than 10 index pages of search results I can't find it, so here goes:

The Olympic AR-15 "Plinker" model has A1 style rear sights. All the information I've been able to find on-line for zeroing an AR-15 is based on the A2 style rear sight. Can someone please either explain how to zero A1 sights, or give me a link to a write-up? I'd be very grateful.

Also ... if anyone owns a Plinker and knows: Are the Oly "A1 style" rear sights really A1, with a close-range and a long-distance aperture? Or are both apertures on the same plane and one just has a bigger hole for use in low light? If they are close-range and long-range ... which is which?

TIA

 

[DMK]

That's easy. For an A1 sight, zero the short range arperture at 50 yards or 200 meters. (Improved Battlesight Zero - IBZ) That will give you +/- 2" out to 200 meters and +/- 1" between 30 yards to 80 yards. Flip to the long range arperture and it will zero at 350 meters (instead of 250m/375m with the "Army A1 zero").

Wait... "bigger hole"? That doesn't sound like an A1 apererture. An A1 has the same size hole, just one's a little higher than the other.

Perhaps it's a "same plane" with a small arperture and a larger "ghost ring" both at the same height. I have one of those on my HD carbine and love it.

Either way, zero the short range arperture at 50 yards. Then flip the sight and see if the elevation changes. If it changes, then you're done. If the elevation doesn't change then refine your zero at 50y with the small arperture(since it will be more accurate).


More info here:

http://groups.msn.com/TheMarylandAR15ShootersSite/zeroingmethods.msnw

 

[Lex]

The Maryland AR site is where the good stuff lives. Lots 'O info there.

Read it, learn it, live it!!!!

Lex

 

[Aguila Blanca]

All the links I found led me to the Maryland AR site.

It doesn't answer my questions. Great for A2s but useless to me.

 

[444]

You are making this far more complicated than it has to be.
The Maryland page is exactly what you need. You simply zero your rifle to hit dead on at 50 yards. That's it. That distance best utilizes the trajectory of the cartridge. This is the superior zero and is far better than anything the military ever used.

 

[Aguila Blanca]

Which way is the sight supposed to be flipped for a 50-yard zero?

And can anyone tell me if the Olympic "Plinker" A1-style rear sight is really an A1 sight (with one aperture for 0-200 yards and the other for 300 yards and greater), or are both apertures on the same plane and one is larger for low light shooting (as has been suggested in several articles my search turned up)?

I know all you guys who DON'T own the same rifle I own think it's simple, but it's not simple when there is no source anywhere in the known universe that answers the question, and the poeple you turn to just say "It's simple."

If it was that simple, I wouldn't have asked the question.

 

[DMK]

Hawkmoon, it actually is pretty simple. But you need to take the rifle out and try it yourself. That will tell you for sure.

On every AR sight I've seen, you flip the sight forward for the close range arperture. Flip it forward and zero at 50 yards. Now flip the sight back (to the long range arperture) and shoot a couple rounds at a fresh target. If the hits are more or less on target then you have a "same plane" sight. If the hits are high, probably off paper, then you don't.

Adjust your front sight for elevation and your rear sight for windage.


You don't have any rear sight elevation adjustments like an A2 sight, so that's all there is to it.

 

[Lex]

From Maryland site:

If your AR-15 with A1 rear sight is using the A2 aperture then you will need to zero using the Improved Battlesight Zero, as both of your apertures are on the same sight plane (theoretically – manufacturing tolerances vary).

1. Flip to the aperture marked "L", use this for zeroing.

2. Fire a 3 shot group. The group should be tight. If it isn’t then practice till it is! Repeat until you get two groups on top of each other.

3. Measure from the center of the group to the expected point of impact. You will need an elevation and a windage measurement.

4. If the group is high or low adjust the front sight. Rotate the sight clockwise to move the point of the bullet impact Up. Rotate the front sight counter-clockwise to Lower the point of impact. For Rifles with an A2 front sight (square post) the movement will be about 3/8 inch per click, the original A1 front sight (round post) will move 0.25" per click for a 20" barrel. For Carbines the movement per click is about 0.5" (Square A2 post), or just over 3/8" using the round A1 post.

5. If the group is to the right or left then the windage disk will need to be adjusted. For Rifles every click moves the point of impact 0.25" at this distance. For Carbines, the point of impact is moved 3/8". Rotate the disk clockwise to move the point of impact to the Right. Rotate the disk counter-clockwise to move impact to the Left.

6. Fire another group to verify the proper point-of-aim/point-of-impact. Repeat steps 3 to 5 as needed.

7. Flip to the unmarked aperture. The rifle now has a 250m battlesight zero, the "L" aperture is used for 375 meter (and longer) shots (or for use when shooting the 25M Schedule ‘C’ Qualification Course – available in the File Cabinet under Targets).

 

[DMK]

If your AR-15 with A1 rear sight is using the A2 aperture then you will need to zero using the Improved Battlesight Zero, as both of your apertures are on the same sight plane (theoretically – manufacturing tolerances vary).

That is incorrect and even contradicted in two other places on the same site. Standard A2 sights definately do not have the arpertures on the same plane. The only difference between A1 and A2 arpertures is the inside diameter of the short range arperture.

Using IBZ with an A2 sight, you zero the long range arperture with the elevation drum bottomed out (after calibrating it for IBZ). When you switch to the short range larger arperture, you need to raise the elevation drum to 8/3. If they were on the same plane, you would not need to do this.

http://groups.msn.com/TheMarylandAR15ShootersSite/sightsopticsfaq.msnw

Q: What is the change of impact between the two apertures in the A2 sight?

A: Courtesy of XS Sights from their website (http://www.aosights.com/news.html FAQ #10)

...Comparing some of the rear sights available today there appears to be 3 variations available. The 1st style (and oldest) has a .014 offset. This gives a 2.52 inch shift in point of impact at 100 yards between the two apertures. The 2nd style has a .017 offset, which shifts point of impact 3.06 inches at 100 yards. The 3rd style has a .024 offset giving a 4.36 inch shift in P.O.I.

All of the points of impact shifts shown above are for the standard barrel AR-15/M-16 that has a sight radius of 20 inches. The shorter sight radius (14.5 inches) of the M4 carbine and weapons of similar configuration increase the amount of point of impact shift. The shifts for these shorter sight radius weapons are 3.48, 4.25, 5.96 inches respectively....

1. Flip to the aperture marked "L", use this for zeroing.

Note: that is the procedure to zero an A1 with the L arperture at 25m for a 250m/375m zero, not for the 200m/350m IBZ. When using the A1 sight with the IBZ, you use the short range arperture, not the L arperture and zero at 50 yards.

Note at the bottom of the IBZ procedure:

Note To Users of Carbines with the A1 style rear sight or users of Flip-Up Sights: This 50 yard zero works really well. If you have the original sight aperture use the unmarked (short range) hole to zero the rifle.

 

[Jenrick]

Okay here are two good resources (if you can find a copy of the Soliders Manual of Common Tasks 1994 edition it'll have this stuff in hard copy).

http://www.infanteristen.dk/download/m16.pdf (your after page 61 of the pdf, or if you print it out page M16-53) Has a step by step list on how to site in.

http://www.infanteristen.dk/download/m16.pdf (page 49 of the pdf) has a discussion on what the various parts of the sight are, didn't see any actual step by step list on siting in.

Hope these help.

-Jenrick

 

[Aguila Blanca]

DMK, Jenrick --

Thank you, Gents. Between the two of you I think I now have enough correct information to head out to the range. DMK -- yes, I know I could just go out there and waste a lot of ammo trying to figure out what's going on, but I just feel a lot more comfotable if I understand something before I get in over my head. You are right that it is simple -- if you have the correct information.

Thanks again.

 

[DMK]

Hawkmoon, you're welcome. That's what we are all here for. Let us know how it works out. I'm curious myself about what kind of sight those Plinkers come with.

And hey, if it's a nice day and you are out shooting your rifle, it's never a waste of ammo!

 

[Aguila Blanca]

Well, I'll have plenty of opportunity to waste ammo. After zeroing the iron sights, I also have to ("want to") zero an AR scope (the 4x type with the turret to adjust from 100 meters out to 500 meters) and a red dot scope. I should have done all this a long time ago, of course, but seeing the news about Noo Ohleens has made it seem like more of a necessity.

It's just so hard to find a range within a half day's drive that allows rifles around here. I envy those who have their own range in the back yard more than anyone can possibly imagine.

 

[rescurat]

Where do I find the file cabinet?

 

[nipprdog]

Where do I find the file cabinet?

Five year old thread.