AR zeroing with A2 sights

[edon]

Having recently purchased a used AR15 A2 (fixed carry handle) 20" barrel, I did a net search on zeroing the sights and came up with a few different options - IBZ, RIBZ, Marine 300m, 50yrd zero, 25yrd zero, etc, etc - everyone has an opinion. So since my range is in meters, basically only out to 200m, it would be nice to have a "zero" setting at 50, 100 and 200m. So please correct me if I'm totally wrong but after reading these different procedures and some people's experences on ar15.com and Maryland AR15 site it seems I'll come close to what I want by doing the following:

1. Adjust rear sight to go 8/3 -3 clicks
2. Flip rear sight to small ap.
3. Set to 8/3 -2 then "zero" at 50m using front sight and rear windage
4. Set to 8/3 -3 and fine-tune zero at 100m using front sight and rear windage

And this should give me approx. zeros at:

1. 50m (8/3 -2)
2. 100m (8/3 -3)
3. 200m (8/3 -2)
4. 300m (8/3)
5. and on depending on setting (4/5/6/7/8)

Am I anywhere close to being on the right track?

 

[koalorka]

Use the standard battlesight zero procedure. First mechanically zero the rifle, simply set the rear elevation knob to its 8/3 position (all the way down until it contacts the carry handle) and make sure the front sight post is flush with the base of the sight housing. Use the smaller (unmarked) aperture. With the unmarked aperture up and the 0-200 m aperture down, rotate the windage knob until you align the index mark on the aperture's hood with the long, white index line on the rear sight assembly. Your rifle's barrel is now aligned with the sights, your point of aim will be were the bullets impacts roughly out to 300 m.

The battlesight zero on the A2 will give you a high-impact probability up to 300 m (using 62 gr. ammunition) since bullet drop is negligible out to 300 m thanks to the SS109/M855's flat trajectory (closer to 250 m with older M193-type 55 gr. ammo). Simply rotate the rear elevation knob counterclockwise 1-click (8/3+1). You're set. Below is a chart that should help you tighten your groups, adjust accordingly, fire for effect!



Hope this helps.

 

[cancer]

I wouldn't call the trajectory "flat" perse. There is an arc, it's just not very big at ranges less than ~300m. 55 and 62 gr rounds zero-ed at 25m will rise and drop back to your zero mark again at ~300m.

Follow the table Koalorka has posted, it will certainly help alot. I believe the table is from the US Amry M16/M4 marksmanship manual. The manual also has ballistic trajectories for different weight rounds.