Armalite M-15A2, 1/9 twist

I got it sighted-in at about 70 yards. However the rear sight had to be raised 6 clicks.  My question is, when I sight in the rifle, shouldn't be the rear sight be all the way down? And from there, adjusting elevation with the front sight?
Please advise.

Secondly, if I move it 6 clicks down until the rear sight touches the receiver, how many turns must I rotate the front sight to get back to the same sight picture?

Also the windage had to be adjusted 10 clicks to the right for it to be on target at 70 yards.

How exactly do I use the rear sight elevation adjustment option?

And, what's the ideal range to sight in the rifle? I hear 30 yards.  I am currently  right on target at 65-70 yards, where should I go from there?

Different sight-in options here:

[url]groups.msn.com/TheMarylandAR15ShootersSite/zeroingmethods.msnw[/url]


I've had great luck with the Improved Battlesight Zero developed by Chuck Santose... Give this one a try and see if it doesn't solve a few of your problems.

[url]groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw[/url]

Rear sight is set to 8/3 -2, with all elevation adjustments made with the front sight.  Set this way, each click of the front sight is just over 1/2" at 50 yards.

[b] (An Improved Battlesight Zero)[/b]

[i] 3. Using a 1/16" Allen wrench loosen the screw (under the revealed hole) in the sight wheel 3 full turns. Leave the wrench in the screw. [/i]


Not sure why this is necessary, but I did this. Will sight it in at 50 yards the next time at the range. I don't really need the 300 meter zero which is standard. Sounds like a better zero.

So, the 50 yard zero is the same as 200 yards. And to get to 300 meters I would have to click to 3/8 mark (2 clicks); to 400m, choose the 4 mark (5 clicks)

[b] ...... Your sights are now zeroed. The large aperture is used for targets between 0 and 250 yards. For virtually this entire distance, the bullet will impact within 2" of the line of sight. [/b]

I've adjusted the sight per directions, but haven't yet zeroed it in at 50 yards.

[b] To engage targets at 300m and beyond, flip to the small aperture. [/b]

I always used the small aperture. This is due to the fact that I didn't know I had the large one for the first several years of owning this rifle. I accidently discovered it fairly recently.  The larger one is quicker however. The small one is very good, gets me small groups.

[b] The default setting is 300m,  [/b]

-- meaning, with it set to 8/3. And all the way down, 8/3 - 2, the setting works out to 200m, do I understand correctly? The article recommends leaving it all the way down, at 200m as default. What are the pros/cons?

[b] and for ranges beyond that, you use the elevation wheel (set to 4 for 400m, 5 for 500m, etc.) up to 800m. [/b]

Understood.

[b]The sights assume a 20" barrel and M855 ammo. ........
[/b]

Yeah, I am using M855 to sight it in.

Large / small aperture has nothing to do with sight adjustment - it's just for more precision.

Anyway, I like this concept better than the one I used previously, sight it in at 25m which is also a zero at 300m.

Chuck's zero assumes a 14.5" M4 barrel shooting M855.  But as you pointed out it works fine out to 400M when using M193 or a 20" barrel.



Small aperture - with the sight bottomed out gives you the most precision possible.  The nice flat 200M trajectory, with the most precise aperture.

The other option is to use the large aperture with the sight set to '3'.  This also uses the flat 200M trajecotry (the large aperture is offset from the small one).  However the large aperture reduces precision - it is however faster and the only way you'll be able to use the irons in low light.

[b] IIRC, there is about 3 MOA of height difference between the apertures. [/b]


Interesting. I made a bad assumption there was no MOA difference.

[b] Small aperture - with the sight bottomed out gives you the most precision possible. The nice flat 200M trajectory, with the most precise aperture.

The other option is to use the large aperture with the sight set to '3'. This also uses the flat 200M trajecotry (the large aperture is offset from the small one). However the large aperture reduces precision - it is however faster and the only way you'll be able to use the irons in low light.  [/b]

OK, now I get it. I reread instructions. It's simple: With the sight all the way down, to 8/3 - 2, use small aperture. If need the large aperture, set the sight to 8/3. (2 clicks up). Both result in the same trajectory.

Seems like within 100m, the large aperture makes more sense. But I never used it before, to be honest. Would be interesting to see if there is any accuracy decrease.