Ordered rear sight parts from Bushmaster to complete an A1-style rear BUIS.
The A2 rear sight flip-up aperture was substituted for the A1 aperture.
Person taking order said it was interchangeable, and that the holes on the A1 type were bigger than the A2. The A2 has the large and small holes.
On an A1 sight/carry handle, has anyone done the A2 sight substitution?
Did the install go o.k., or is there anything to be aware of?

Yes, it will work, but there will be less available windage since the A2 sight body is larger than the A1.  I put an A2 sight on a C7 upper recently, and only had 22 clicks from left to right.  I had to zero with 14 left, but could only go 11 from center.  I went back to the A1 sight.

The distance between the ears of the BUIS I'm installing it on is a little bit narrower than the distance on the carry handle sight.
Are both apertures/holes on your A1 larger than the smallest on the A2?

Quoted: The distance between the ears of the BUIS I'm installing it on is a little bit narrower than the distance on the carry handle sight. Are both apertures/holes on your A1 larger than the smallest on the A2?

Bump.

I would also like to know this.

Also, how useful is the large aperture on the A2 in general. Is it really that much better for CQB and/or at night (compared to the A1)?

Also, where is a good place to order just the A2 apertures (not the entire sight assembly)?

Are you talking about the CNC Machining A1 carry handle?  I put an A2 rear sight apeture on it, and like the A1/C7 upper, only get 22 clicks from side to side.

I've got a C7 upper and A1 upper with A1 apetures, and yes, the apetures are larger than the smaller A2 apeture, and you should get a little more windage out of it than an A2.

I believe the A2 apeture is more versatile because you can use the big hole for night shooting, and the small hole for day shooting.  The small hole helps with distance shooting.  As for is the large hole useful...I honestly don't know.  The only time I switched apetures that I can remember was for masked fire as part of the basic rifle marksmanship qualification.

Fulton Armory may be another option for A1 rear sights if Bushmaster is out.

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Quoted: Are you talking about the CNC Machining A1 carry handle?

I may not be understanding your statement correctly, but do you have to make any other modifications if you just want to substitute the A2 apertures for the A1's?

?

(bump)

The A2 sight aperature works fine on any A1 sight.  In fact many people swap out the A1 sight for the A2 on their older rifles as the A2 is considered better. I did it on one of mine with no problems.

The A1 sight has two small aperatures, one that is for longer distance (200 meters and up) shooting and one for less than 200 meters.  The A2 sight is an improvement as they make the short range aperature larger, as at very close range the A1 aperature constricts your field of view.  They are a straight swap, no problem, and if no one had told you I bet you would not even have noticed!


Did you decide to stick with the CNC A1 BUIS?  Let us know how it works out.

Quoted: Quoted: Are you talking about the CNC Machining A1 carry handle? I may not be understanding your statement correctly, but do you have to make any other modifications if you just want to substitute the A2 apertures for the A1's?

Nope.  No mods are necessary.

Quoted: The A2 sight aperature works fine on any A1 sight.  In fact many people swap out the A1 sight for the A2 on their older rifles as the A2 is considered better. I did it on one of mine with no problems. The A1 sight has two small aperatures, one that is for longer distance (200 meters and up) shooting and one for less than 200 meters.  The A2 sight is an improvement as they make the short range aperature larger, as at very close range the A1 aperature constricts your field of view.  They are a straight swap, no problem, and if no one had told you I bet you would not even have noticed! Did you decide to stick with the CNC A1 BUIS?  Let us know how it works out.

The A2 sight parts will be going on the CNC A1 BUIS.
Am sticking with it for now. When the ordered sight parts show up from Bushmaster, a thorough test will be done. Looks like the sight parts may be delayed, judging from a look at recent weather in Maine.
If someone wants to pay $95 for the stripped/no parts sight as I received it, I may consider parting with it. Listed at EE, but no offers.  
Good concept for a BUIS with great machining, but an item or two I'm still wondering about which have been discussed elsewhere.
I also have an Armalite A2 carry handle. The apertures on it are both the same size, and small. Was told and read that this is a "Match" aperture size and flip sight. Haven't went to the source to verify. Also, I haven't measured the aperture sizes on the Armalite handle.

Thanks all for the useful info.  

I used to have several A1 uppers, and swapped in the A2 rear blade, and at the same time put on Rapidex Windage Knob.  Also, I swapped in the A2 square front sight post for a sharper image.

This is something I highly recommend to shooters with A1 uppers.  For minimal cost you have upgraded to near A2 performance.

I actually prefer the KISS of the A1 upper with A2 parts over the full A2 upper.

I have since switched ALL of my AR's to flattup uppers.