A2 sight questions

[Txs]

I'm a bit old school and have used A1 sight equipped rifles for many years, first in the military and then as a patrol rifle. Due to the market these days I'm having to learn the finer points of A2 sight system use.

The situation I'm faced with is these sights are calibrated for use of M855 ammunition, but my issue ammo is 55gr. stuff and I'm using a non-GI barrel.

When using a 16in/1-9 barrel carbine equipped with A2 sights and firing this lighter bullet, what will be the distance of my actual point of impact at the various ranges marked on the sight drum?

Also, will there be any difference in these impact points if I'm using a 6/3 or 8/3 sight drum with this ammo/barrel combination?

I plan on shooting my issue ammo at these various ranges/settings to determine this, but does anyone have an idea what results I can expect?

[AMMOTECH]

I've got a 14.5" 1/9 A2 sights (cut removable carry handle with 6/3 markings) with a 50 yard zero using XM193 55 gr ammo. I only have about an 2" difference from POA/POI from 10-300 M.
A lot of it has more to do with your zero then the ammo but once you have a zero for one weight of ammo the your POA/POI will be off if you change bullet weights.

The 6/3 8/3 is for shooting out pass 300M to 600/800M. You will have either a 6 or an 8 based on the type of carry handle that you have.

Couple of questions for you:
Do you have a fixed carry handle or removable?
Who made your upper/barrel?

I'm sure there will be a few guy's on here that will explain it a lot better.

[Eric]

If this is to be deployed as a patrol carbine, I don't foresee many situations where you would need to dial up the elevation, especially with a 50 yard zero. You're good out to about 200M with minimal POI shift.

[GaryXD]

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

[Txs]

I've always used a 50yd. zero with A1 sights in order to give me that nice flat trajectory out to 200yds and this is what I'm currently doing with my A2 sighted/fixed carrying handle Bushmaster. The reason I also asked about the 6/3 drum is for my fellow officers who are using detachable handle models with this same barrel type. My agency issues AR's, but personally owned weapons of specified manufacture are also allowed.

I agree that, for a variety of reasons, a patrol rifle is almost exclusively going to be a 100-150 yd. rifle. The reason for my original question is that if I'm carrying a rifle with a graduated rear sight I'd like to at least have an idea of how each setting would hit if the freak need for long range fire were to arise. Otherwise, what's the benefit of having this more complex and expensive to manufacture system stuck on my weapon?

Personally, I don't understand why the major manufacturer's "patrol rifle" models aren't offered with an A1 sight using an A2 type aperture system. This rugged and foolproof-zero-hold sight, when combined with a large 0-200 aperture for low light use, makes more sense for general issue to patrol officers. The carbine length barrel is good for ease of deployment from vehicles, but putting an adjustable sight on one that's calibrated for a full length barrel is impractical. Without equipping these with a sight drum calibrated for the 20% shorter barrel, or at least supplying various bullet weight data for the sight that's used, they're adding a useless element to the weapon that can much more easily become placed out of proper adjustment. I'm a firm believer in the KISS principle and the factory set-ups currently being offered fly in it's face.