Dumb question - "A-1" sights

lazyeye · Aug 19, 2023

I feel like a dummy for having to ask this, and the owners handbook doesn't shed any light and my googling is fruitless. My first AR-15 that I bought in circa 2008 is a Olympic Sporter. It's a 16" carbine with an A1 style upper, 1:9 barrel. It has two aperture rear sights, one is blank the other is labeled "A-1". I don't shoot it much any more but I'm getting interested in doing things right so I want to know more about how I'm supposed to use the sights.
My question is this: Is there a blanket answer for what the difference is between the blank sight and the "A-1"? I'm pretty sure "A-1" is for longer range, but how much longer? Am I supposed to zero the blank sight at X yards and that means when I flip to "A-1" that means it's zeroed at X+Y yards?

Stomper · Aug 19, 2023

It's mainly the rear aperture diameter. On a set of A1 irons the larger aperture is typically 0-200m (and not labeled) the smaller aperture is (typically) for 250-400m (USGI irons were marked "L")

Assuming you have a 20" A1 barrel, use the blank sight (it should be the larger aperture of the two) and perform what's called a "battle-sight zero" at 25m, this will (in theory) give you the same POI at 250m.

Here's an informative read on using AR irons.

The Ultimate Guide to the AR15 Iron Sights Ver 1.1 - The New Rifleman

Irons these days are just misunderstood. You want to master iron sights before moving on to a optics? You need knowledge. Where is the knowledge? Right here.

thenewrifleman.com

Koda · Aug 19, 2023

Stomper said:
Assuming you have a 20" A1 barrel, use the blank sight (it should be the larger aperture of the two) and perform what's called a "barrel-sight zero" at 25m, this will (in theory) give you the same POI at 250m.

I always thought you zeroed using the smaller aperture since its more accurate?

lazyeye · Aug 19, 2023

It's a 16" barrel and I can't tell a size difference between the apertures, they're both pin holes. The manual I received with the rifle describes an A2 sight setup with the obviously larger (ghost ring) sight and the pin hole aperture.

Stomper · Aug 19, 2023

Koda said:
I always thought you zeroed using the smaller aperture since its more accurate?

Not for 20" A1 battle-sight zero, you're shooting at a target 25m away from the firing line.

lazyeye · Aug 19, 2023

Here's what they look like. Both pin holes, but the A-1 *seems* to be slightly higher.

Stomper · Aug 19, 2023

lazyeye said:
It's a 16" barrel and I can't tell a size difference between the apertures, they're both pin holes. The manual I received with the rifle describes an A2 sight setup with the obviously larger (ghost ring) sight and the pin hole aperture.

Sounds like you may have a custom "house" setup, plus the battle-sight zero for a 16" bbl with carbine length sight radius is a bit different, there's also an "improved" battle-sight zero for the carbine radius. Google it up!