A2 apreture for A1 upper reciever?

[1986s4]

Does anyone make such a beast?

[mack7.62]

I think the A2 fits a A1.

[Lincoln7]

Yep, I swapped mine out with an A2 I bought from Brownells. Fit just fine

[jsbhike]

As long as you don't get a Chinese knock off (odd ball threads) or some obviously special aperture set up (Troy replacements come to mind) they will interchange without issues.

Weaver/Blackhawk same plane apertures have the correct threading, but have other issues with thickness that make them not play well in most(maybe all) standard rear sight assemblies without modification.

[dmaxfireman]

I have an A1 receiver with an A2 aperture. No problems.

[AndyLate]

As long as you don't get a Chinese knock off (odd ball threads) or some obviously special aperture set up (Troy replacements come to mind) they will interchange without issues.

Weaver/Blackhawk same plane apertures have the correct threading, but have other issues with thickness that make them not play well in most(maybe all) standard rear sight assemblies without modification.

That was certainly true of my Blackhawk same plane aperture when used with an A2/ M4 carry handle sight.

[lysander]

The A2 rear sight is wider than the A1 sight, so you don't get as much windage adjustment in an A1.

There are a number of other non-obvious dimensional differences, but you can swap them.

[jsbhike]

I would actually vote for XS same plane or the M16/M16A1 LLLSS (maybe I got the right number of each letter) rear aperture.

https://www.bevfitchett.us/rifle-5-56mm-m16-m16a1/low-light-level-sight.html

[26 Inf]

I would actually vote for XS same plane or the M16/M16A1 LLLSS (maybe I got the right number of each letter) rear aperture.

https://www.bevfitchett.us/rifle-5-56mm-m16-m16a1/low-light-level-sight.html

I don't know if you were trying to link to this sight, but it is the way I would go. Same plane with a CQB notch. I didn't jump in and suggest it because it is is the $35.00 price range compared to $8.00 for the standard A2, and didn't know what the OP's intended use was.

Here's a review: https://civiliangunfighter.wordpress.com/2015/12/16/csat-rear-sight-review/

Here's a link to the sight at $35.92: https://www.brownells.com/rifle-parts/sights/rear-sights/ar-15-csat-combat-rear-sight-prod26948.aspx

[jsbhike]

I don't know if you were trying to link to this sight, but it is the way I would go. Same plane with a CQB notch. I didn't jump in and suggest it because it is is the $35.00 price range compared to $8.00 for the standard A2, and didn't know what the OP's intended use was.

Here's a review: https://civiliangunfighter.wordpress.com/2015/12/16/csat-rear-sight-review/

Here's a link to the sight at $35.92: https://www.brownells.com/rifle-parts/sights/rear-sights/ar-15-csat-combat-rear-sight-prod26948.aspx

I was thinking of the standard XS since it is more inline with stock A1/A2 design, but I have and like the CSAT version also. At least for now until aging eye sight eats the notch, but that isn't a knock on the CSAT.

[1986s4]

Thanks all. I'm shooting a match tomorrow with the A1 upper so we'll see how it goes. An A2 rear may not be necessary. I installed a KNS globe type front sight post, the medium size one which seems rather small through the A1 aperture. I painted the little round ball on top gold to pick up light, much like the brass/gold beads on pistol front sights.

[jsbhike]

If I found the right numbers, apertures are:

A2 is 1.75mm and 5mm
A1 is 2mm each
LLLSS is 2mm and 7mm
XS is .100"/2.54mm and .230"/5.842 mm

I would assume CSAT is the same as standard, but not seeing numbers on XS site and not sure where the packaging on mine is or even if it has aperture diameters.

[lysander]

If I found the right numbers, apertures are:

A2 is 1.75mm and 5mm
A1 is 2mm each
LLLSS is 2mm and 7mm
XS is .100"/2.54mm and .230"/5.842 mm

I would assume CSAT is the same as standard, but not seeing numbers on XS site and not sure where the packaging on mine is or even if it has aperture diameters.
It's an American design....

0.197", .070", and 0.080"

:D

[jsbhike]

It's an American design....

0.197", .070", and 0.080"

:D

I wondered about that too. :confused:

Got the A2 and LLLSS metric diameters out of the paper done by the Army on why they didn't want the M16A2.

XS gives imperial measurements so I got curious if theirs matched A1 or A2 and ran the conversion on it to be consistent.

[1986s4]

I thank you all for your answers to my question. During the match I found the A1 rear aperture combined with the KNS pin w/ball front to be a great combination. The gold paint was a good addition and my middle age eyes agreed. Despite the constant rain, being cold and soaked I had no trouble hitting man size steel at 150m. Important tip: a mere drop of water can occlude the peep, blow it out before trying to shoot....
Observation: My squad mates who were sporting RMR's on their pistol were having issues with a blurry sight picture due to the constant rain.