Question on zeroing AR15 at 100 yards for 300 yards.


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tju1973
March 31, 2010, 06:46 PM
I feel bad about this, but it has been 13 years since I carried one-- I am taking my AR15 out this weekend to sight it in and test several ammo makes.

That being said, our range only goes to 100yards, but I want to zero it for 300-- Do you know how high my groups should be hitting if I use my 300 yd dope at 100 yards?

Ironically, I was a PMI my last 2 years in the Corps, and a Grunt(0331) for the rest of my 6 years/...time and hard living have not been kind to my brain..:(

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Quentin
March 31, 2010, 06:53 PM
It depends on your barrel length and the ammo you'll be using. For an M4 clone you can zero at 25 meters and will also be zeroed at 300 meters, much like you did in the service. To zero at 100 meters you'd want your group to be about 5.3" high to give you a 300 meter zero. For a 20" barrel you'd group about 4.4" high at 100 meters or 0.33" low at 25.

Yards will skew things slightly but meters will get you close.

ETA: 62 grain military ammo...

61chalk
March 31, 2010, 07:19 PM
I wish I could remember where on the web I saw this, but a Marine had
came up with what I thought was a better way of zeroing by utilizing the
flat shooting AR....you don't have the "military zero or high ark"...just food
for thought because I'm finding I like it...Even with A scope mount on top
the handle I've sighted mine in to hit about 1" low at 50 yds. an it hits 1/4"
high at 100 yds, 1/2" high at 220 yds....for the 300 yds I aim 10" high. When
hunting this gives me pretty much dead center shots out to 250 yds.

tju1973
March 31, 2010, 07:35 PM
It depends on your barrel length and the ammo you'll be using. For an M4 clone you can zero at 25 meters and will also be zeroed at 300 meters, much like you did in the service. To zero at 100 meters you'd want your group to be about 5.3" high to give you a 300 meter zero. For a 20" barrel you'd group about 4.4" high at 100 meters or 0.33" low at 25.

Yards will skew things slightly but meters will get you close.

ETA: 62 grain military ammo...
18", 1/7"-- Probably will only shoot 55grn soft points this weekend-- I plan to resight it in with a scope one I get some 77 Grain Black Hills..I probably will mainly shoot 55grn- 62grns (I know the zero for each is different)--

DOn't know if that helps--

just read-- I am guessing close to 5" high then out of my barrel..Thanks!

wcwhitey
March 31, 2010, 09:03 PM
Her you go 61Chalk. http://www.fsguns.com/ibsz.html This will give you good information. Bill

tju1973
March 31, 2010, 09:09 PM
Her you go 61Chalk. http://www.fsguns.com/ibsz.html This will give you good information. Bill
Awesome-- that is exactly what I was looking for-- and to be honest, I was puzzled why my read sight was marked 6/3 and would not go -2 ..Now I know...

Now to locate a 1/16" allen wrench...

Quentin
March 31, 2010, 10:53 PM
Yes, Col. Santose' Improved Battlesight Zero is excellent. But with a removable carry handle you need to go down to -4 not -2. You may also want to look at Molon's clever Revised Improved Battlesight Zero:
http://www.ar15.com/forums/topic.html?b=3&f=18&t=328143

When you find the allen wrench, you'll have to crank the elevation wheel a little more - down to -6 or -7 if you want to play with the RIBZ. (In addition to the fantastic IBZ, RIBZ will give you a 100 yard zero if you click down to -6. But make sure you have enough adjustment in your front sight.)

61chalk
April 2, 2010, 10:39 AM
Thanks wcwhitey...! Going to get that put on my favorites right now.

Bula
April 2, 2010, 12:39 PM
I learn something new here everyday, thank you gentlemen. Lots of good stuff. Going to dust off the AR and get to the range.

Barker45
April 2, 2010, 12:39 PM
I much prefer the 50/200m zero also. The 300m zero has you shooting way high at 100m. The 50/200 zero will have you shooting a couple of inches high at 100, dead on a 200, and a couple of inches low at 300 making COM hits much easier. You don't have to use the directions in the links provided. Bottom out you rear sight and then use your front sight to adjust the POI at 50 meters. After zeroing at 50, confirm at 100, 200, 300 when available. Also confirm your POA/POI at closer ranges in order to learn your off-aim at CQB distances. Once zeroed with your prefered amomo, confirm before each range session or if you change ammo. Good luck and have fun!

wcwhitey
April 2, 2010, 09:06 PM
I agree Barker. This is why I use the 50 yard zero on my carbines. I believe in the K.I.S.S principle. I just want to pick it up and be able to reliably make hits from 0 - 300m without a sight change.

ny32182
June 18, 2010, 12:01 PM
I've got a question for the group. The zeroing procedures never seem to bring the aperature into play. Do you do your zero with the large ap (marked 0-2) or the small? How is it affected when you flip?

KW
June 18, 2010, 12:19 PM
Zero with the small aperture. At the low 6/3 setting you will have a 300m zero with the small aperture and a 200m zero with the large aperture.

ny32182
June 18, 2010, 12:31 PM
So just to make sure I am understanding this 100%, according to the standard military procedure, you use the small app to achieve the 25/300 zero with the rear drum set at the 6/3 position. From there, staying with the small app, you can rotate the drum to 4, 5, or 6 side of the 6/3 as applicable and be on at those ranges.

With the rear drum at the 3 position of the 6/3 setting, with the sights set as described above, flipping over to the large app will give a 200 yard zero?

Quentin
June 18, 2010, 05:53 PM
ny32182, yes you've got it right (for the M4). For the standard military battlesight zero of the M4 carbine you use the small aperture and crank the elevation knob down to 6/3 (the 300 meter setting, don't crank all the way up another revolution to 6/3 for 600 meters) and leave it there. Then zero at 25 meters using the front sight for elevation adjustment and rear for windage. Now you have a 25/300 meter zero.

Now for the 20" M16A4 you zero at 25 meters with the elevation knob at the little "z" instead of 6/3 then when done click back two clicks to 6/3 for a 300 meter zero.

After proper BZ you turn the elevation knob to 4 for 400, 5 for 500 and the upper 6/3 for 600 meters. With the sights set to 300 meters flipping to the large aperture gives you a rough 200 meter zero but really it's only considered useful for within 200 meters or in low light situations.

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