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Thread: Zeroing an ACOG - Help a Confused Brother Out

  1. #1
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    Zeroing an ACOG - Help a Confused Brother Out

    I've been reading online for a while and have reached the point where I'm just confused. I want to zero my 4X ACOG for my 14.5" Colt SOCOM rifle. I do not have access to a 100 meter range target, only 100 yards (fixed target stands). I want to 100 meter my ACOG so I get the best possible performance out of it. I am assuming it is calibrated for the 62gr M855 round, correct? So that's one thing. I should zero it with that ammo, but am unclear what results I'll get if I use 55gr or 77gr bullets. I should zero it at 100 meters, but again, I do not have access to a 100 meter distance. I can probably get a good 25 meter target set up, but then I'm not at 100 meter.

    Your advice would be appreciated.
    Last edited by CAMagnussen; 11-17-19 at 15:43.

  2. #2
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    If you absolutely, positively must zero closer than 100:

    The tip of the vertical stadia is your POA at 25m with the POI being 1.5cm low. This is, as you know, a compromise, but will be the best you can do with what you have. It will also set you up for success before pushing back to 100 when/if the opportunity presents itself and you get the chance to truly dial your optic in.

    POI out to 300 is fairly similar within the spectrum of 55-72g ammo, but it starts to rather significantly deviate past that. As for what to expect, use the Strelok app and see what you get.

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    Zero with the ammo you are going to shoot with. Most ammo will have different DOPE. I liked to zero at 300 to 500 meters with the 3/500 meters hash mark, then figure out where I will hit at 100 etc. The further out you zero the better you will know your come ups per se.

    Zero at 25 meters is a last case scenario choice. But it will get you close, but understand all ammo will have different DOPE. ACOGS are not super precision based but I love them for a great battle optic.

    You could make a DOPE sheet for different ammo that you use. ie, you might have to hold 550 to get hits with 55grain soft shooting ammo at 500. If you only shoot one ammo choice it simplifies things. I shoot 77grain ammo and set my ACOGS based on that ammo.

    PB
    "Air Force / Policeman / Fireman / Man of God / Friend of mine / R.I.P. Steve Lamy"

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    Quote Originally Posted by CAMagnussen View Post
    I've been reading online for a while and have reached the point where I'm just confused. I want to zero my 4X ACOG for my 14.5" Colt SOCOM rifle. I do not have access to a 100 meter range target, only 100 yards (fixed target stands). I want to 100 meter my ACOG so I get the best possible performance out of it. I am assuming it is calibrated for the 62gr M855 round, correct? So that's one thing. I should zero it with that ammo, but am unclear what results I'll get if I use 55gr or 77gr bullets. I should zero it at 100 meters, but again, I do not have access to a 100 meter distance. I can probably get a good 25 meter target set up, but then I'm not at 100 meter.

    Your advice would be appreciated.
    On a ballistic chart, 100yd vs 100m is 0.1”. Just zero at 100yds.
    Verify at further distances if you ever get the chance

  5. #5
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    Quote Originally Posted by MegademiC View Post
    On a ballistic chart, 100yd vs 100m is 0.1”. Just zero at 100yds.
    Verify at further distances if you ever get the chance
    Solid advice.
    "Air Force / Policeman / Fireman / Man of God / Friend of mine / R.I.P. Steve Lamy"

  6. #6
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    We just zero everything at 100 yards. We're not shooting M855 anyway, so we just check our POI at distance and note if 500 (for example) tracks. Or if in fact, you need a little more or less hold over.

    Generally speaking, the COG reticles track pretty well with 77 gr match style ammo.
    "You people have too much time on your hands." - scottryan

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    Zeroing an ACOG - Help a Confused Brother Out

    I would agree about zeroing at 100 yds and verifying at the other distances. You’ll probably be very close.

    If you really want to do it right, you can “recalibrate” the reticle for your ammo and barrel length with a chronograph and by getting the subtension drops (MOA) from Trijicon for your reticle.


    Sent from my iPhone using Tapatalk
    Last edited by pomyc; 11-18-19 at 21:41.

  8. #8
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    Quote Originally Posted by CAMagnussen View Post
    I've been reading online for a while and have reached the point where I'm just confused. I want to zero my 4X ACOG for my 14.5" Colt SOCOM rifle. I do not have access to a 100 meter range target, only 100 yards (fixed target stands). I want to 100 meter my ACOG so I get the best possible performance out of it. I am assuming it is calibrated for the 62gr M855 round, correct? So that's one thing. I should zero it with that ammo, but am unclear what results I'll get if I use 55gr or 77gr bullets. I should zero it at 100 meters, but again, I do not have access to a 100 meter distance. I can probably get a good 25 meter target set up, but then I'm not at 100 meter.

    Your advice would be appreciated.
    0.304g1 @ 2900

    Adjust as needed.

  9. #9
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    Quote Originally Posted by MegademiC View Post
    On a ballistic chart, 100yd vs 100m is 0.1”. Just zero at 100yds.
    Verify at further distances if you ever get the chance
    And if he plans on using green tips it really won't matter! Tip on zeroing 855... Shoot 10 rounds and adjust the scope zero to the center of the group. If you try to shoot a single round and adjust you never will get it zeroed. Down south we call that chasing your tail.

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