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Posted: 1/15/2015 12:59:24 AM EDT
Help me think this through.

I'll confirm down the road when I have access to 100m, but for a basic zero, do I use the 300m mark at 25y for the zero?
Link Posted: 1/15/2015 1:08:15 AM EDT
[#1]
We zeroed initially at 33 meters (36 yards) using the 300 meter POA, that should get you close on the 100 meter POA, then confirm at 100.

That's a TA31RCO, it will probably be different for other models with different BDCs.
Link Posted: 1/15/2015 1:08:32 AM EDT
[#2]
50 work bedder.

Link Posted: 1/15/2015 1:10:56 AM EDT
[#3]
Based upon some charts I made, for a 55 gr bullet moving out at 3086 fps at the muzzle (about a 16" barrel) the bullet will be about 1.5" low at 25 yards. It will be about  1.5" low once again at 180 yards.

BC = .243

So use the 200 yards setting.
Link Posted: 1/15/2015 1:17:01 AM EDT
[#4]
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Quoted:
50 work bedder.

http://i49.tinypic.com/15n9742.jpg
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For ACOG I'd want to use 100 like the instructions say.

And for that purpose, 100 works better. Because most of the way out to 150 you are almost dead nuts on. And that represents the most likely range you will shoot at. For longer range use the different ranges in the ACOG.

For a red dot sight I'd probably opt for a 75 yards zero. The 50 yard zero doesn't show an advantage until you get past about 190 yards.
Link Posted: 1/15/2015 1:18:15 AM EDT
[#5]
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Quoted:
50 work bedder.

http://i49.tinypic.com/15n9742.jpg
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You miss the part about this being an ACOG?

Aimpoint is zero'd at 50.
Link Posted: 1/15/2015 1:18:52 AM EDT
[#6]
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Quoted:
Based upon some charts I made, for a 55 gr bullet moving out at 3086 fps at the muzzle (about a 16" barrel) the bullet will be about 1.5" low at 25 yards. It will be about  1.5" low once again at 180 yards.

BC = .243

So use the 200 yards setting.
View Quote


Use the 200y setting as POA instead of 300?
Link Posted: 1/15/2015 1:23:35 AM EDT
[#7]
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Quoted:


Use the 200y setting as POA instead of 300?
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Quoted:
Quoted:
Based upon some charts I made, for a 55 gr bullet moving out at 3086 fps at the muzzle (about a 16" barrel) the bullet will be about 1.5" low at 25 yards. It will be about  1.5" low once again at 180 yards.

BC = .243

So use the 200 yards setting.


Use the 200y setting as POA instead of 300?


That's what my chart is showing.
Link Posted: 1/15/2015 1:25:22 AM EDT
[#8]
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Quoted:


You miss the part about this being an ACOG?

Aimpoint is zero'd at 50.
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Quoted:
Quoted:
50 work bedder.

http://i49.tinypic.com/15n9742.jpg


You miss the part about this being an ACOG?

Aimpoint is zero'd at 50.


I made my charts to decide if 50 was better then 100 or 75 for a red dot. I like 75 best.
Link Posted: 1/15/2015 1:26:25 AM EDT
[#9]
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Quoted:


I made my charts to decide if 50 was better then 100 or 75 for a red dot. I like 75 best.
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Quoted:
Quoted:
Quoted:
50 work bedder.

http://i49.tinypic.com/15n9742.jpg


You miss the part about this being an ACOG?

Aimpoint is zero'd at 50.


I made my charts to decide if 50 was better then 100 or 75 for a red dot. I like 75 best.


Right, but the entire BDC is screwed up if the designed POA is not at 100
Link Posted: 1/15/2015 1:30:19 AM EDT
[#10]
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Quoted:


Right, but the entire BDC is screwed up if the designed POA is not at 100
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I was talking to red dot/eotech.

For ACOG, yeah, 100. As it is, even for a red dot the 100 yard zero is better the 50 out to 180 yards at least.
Link Posted: 1/15/2015 1:31:44 AM EDT
[#11]
Send it to me and I'll zero it.
Link Posted: 1/15/2015 1:32:44 AM EDT
[#12]
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Quoted:
Send it to me and I'll zero it.
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Ha we just need to get out and shoot homie.
Link Posted: 1/15/2015 1:37:05 AM EDT
[#13]
Google searching comes up with 300m mark at 25y is about as close as I'll get until I'm able to actually shoot outside
Link Posted: 1/15/2015 1:37:33 AM EDT
[#14]
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Quoted:


Ha we just need to get out and shoot homie.
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Quoted:
Quoted:
Send it to me and I'll zero it.


Ha we just need to get out and shoot homie.

My local range is doing CCW scenarios at dusk Friday.
Link Posted: 1/15/2015 1:38:48 AM EDT
[#15]
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Quoted:

My local range is doing CCW scenarios at dusk Friday.
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Quoted:
Quoted:
Send it to me and I'll zero it.


Ha we just need to get out and shoot homie.

My local range is doing CCW scenarios at dusk Friday.


I'm hoping to be asleep by then, flipping my stupid night shift schedule to go out for 'yotes Saturday at dawn.

But that'd be a great thing to do
Link Posted: 1/15/2015 1:40:51 AM EDT
[#16]
I hate you. I wanna hunt 'yotes.  Missed my chance at hunting mountain lion this summer, too.
Link Posted: 1/15/2015 1:43:30 AM EDT
[#17]
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Quoted:
I hate you. I wanna hunt 'yotes.  Missed my chance at hunting mountain lion this summer, too.
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Coworkers parent's land, we'll see how it goes.  I want to start finding a few places we can go.  I'll keep you updated when I get thing lined up.
Link Posted: 1/15/2015 1:43:53 AM EDT
[#18]
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Quoted:
Google searching comes up with 300m mark at 25y is about as close as I'll get until I'm able to actually shoot outside
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Google? Use a ballistics program. It looks to me like 300 yards puts you about 10" high from where you want to be.

Using the 100 yard setting should put you about 1.5" high at 25. You would be better off using that then the 300.
Link Posted: 1/15/2015 1:46:50 AM EDT
[#19]

Link Posted: 1/15/2015 1:47:36 AM EDT
[#20]
^ Exactly, that's what I keep reading on M4C, etc.

Those are in meters though, indoor range is yards, I'm almost positive
Link Posted: 1/15/2015 1:54:03 AM EDT
[#21]
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Quoted:
^ Exactly, that's what I keep reading on M4C, etc.

Those are in meters though, indoor range is yards, I'm almost positive
View Quote


Well, I think that will put you about 10" high. The 200m setting perhaps isn't the best for precise shooting so I can see why you wouldn't want to use that. I'd go with the 100m.

Try either 100 or 300 and let me know if I was right.
Link Posted: 1/15/2015 1:55:55 AM EDT
[#22]
Link Posted: 1/15/2015 1:57:42 AM EDT
[#23]
i dont know why people are giving all of these different ranges to zero at.  zero like the manual says (like the image i posted) and that will allow the use of the BDC in the reticle for automatic proper hold over
Link Posted: 1/15/2015 2:01:03 AM EDT
[#24]
You can just spitball it, 25 yards is close, 36 is better. The adjustments are 3 clicks per inch at 100M or 9 per at 33M, whatever that works out to at 25 yards. Divide yards by 1.1 for roughly equivalent meters.

You should be low at 25 yards, not sure by how much.
Link Posted: 1/15/2015 2:23:02 AM EDT
[#25]
Remember, they are made in meters not yards.  The 300 meter line will be roughly on at 25 meters, the 200 meter line will be roughly on at 50 meters.  

Of course that only applies if the model of ACOG, bullet weight, velocity/barrel length are compatible.  AND some ACOGS are designed to be mounted on a 'flattop' and some are set for mounting on a carry handle, Is yours is not a match then everything is off.  

For many purposes, out to 200 yards or meters there is probably not much difference unless you are using very heavy bullets, but for best results, do your zeroing in meters.
Link Posted: 1/15/2015 2:26:28 AM EDT
[#26]
Yeah, thank you.  It's cold outside, and I don't currently have the land available to me that I shoot on, so my only option is a 25y indoor range.  Not ideal, I was hoping for a decent solution but it doesn't look like there is one.
Link Posted: 1/15/2015 2:27:55 AM EDT
[#27]
25yds to get on paper, then 100yds.
Pretty sure 100 is in the manual.
Link Posted: 1/15/2015 2:28:04 AM EDT
[#28]
Link Posted: 1/15/2015 2:28:25 AM EDT
[#29]
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Quoted:
25yds to get on paper, then 100yds.
Pretty sure 100 is in the manual.
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Yeah apparently I needed to be more clear on how ACOGs work in OP.
Link Posted: 1/15/2015 2:28:47 AM EDT
[#30]

Link Posted: 1/15/2015 2:30:43 AM EDT
[#31]
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Thanks, saved to my phone.
Link Posted: 1/15/2015 2:42:43 AM EDT
[#32]
Ok I punched some round numbers into a ballistics program and I think you should be about 1" low at 25 yards. That's using the 300M POA on the reticle.

That will be about the same as shooting the same POA at 36 yards (33M), that's about the best you can do with the off range. I had to do the same thing at a 25 yd indoor range a while ago.

If you know your exact height over bore, muzzle velocity, and other relevant info, you can get even more accurate, but that should be close I think.
Link Posted: 1/15/2015 3:33:23 AM EDT
[#33]
Use 50.  It's dead nuts on (within 2") from 30 yards to about 230 yards.  A 25 yard zero will have you missing high on anything smaller than beach ball on targets over the likely ranges you'll be firing at.
Link Posted: 1/15/2015 3:49:53 AM EDT
[#34]
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Quoted:
Use 50.  It's dead nuts on (within 2") from 30 yards to about 230 yards.  A 25 yard zero will have you missing high on anything smaller than beach ball on targets over the likely ranges you'll be firing at.
View Quote


I disagree.  If you're using the 300 meter post at 25 yards for zeroing, then using the tip of the chevron or horseshoe dot for engaging targets inside 300 meters, you should be basically dead on.  Not inches high...you're compensating for that when using the different aim point on the reticle.

OP, I zeroed at 25 yards with mine using the tip of the 300 meter post and that's pretty damn close.  It may be possible to get it closer if you're using 3X meters on the tip of the 300 meter post, but for simplicity you can rely on the 25 yard zero IMO.  That's what I do and it just plain works.

It is important to note though that it's really all dependent on the projectile and the barrel characteristics that the ACOG is calibrated for.
Link Posted: 1/15/2015 4:02:03 AM EDT
[#35]
Link Posted: 1/15/2015 4:05:15 AM EDT
[#36]
Holy shit people, how hard is it to figure out what the OP is trying to do.

He ONLY HAS ACCESS TO A 25YARD RANGE IN THE IMMEDIATE FUTURE.  NOT 36, NOT 50, NOT 100.

He'd LIKE TO GET HIS ACOG set to  AN APPROXIMATE 100 METER ZERO in the mean time.  What mark on the reticle does he have to use to approximate a 100meter zero if he only has 25 yards to work with?

Jesus fucking Christ.



Link Posted: 1/15/2015 4:07:34 AM EDT
[#37]
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Quoted:
Holy shit people, how hard is it to figure out what the OP is trying to do.

He ONLY HAS ACCESS TO A 25YARD RANGE IN THE IMMEDIATE FUTURE.  NOT 36, NOT 50, NOT 100.

He'd LIKE TO GET HIS ACOG set to  AN APPROXIMATE 100 METER ZERO in the mean time.  What mark on the reticle does he have to use to approximate a 100meter zero if he only has 25 yards to work with?

Jesus fucking Christ.



View Quote


Asked and answered, like 5 times at least.  Use the tip of the 300 meter post, period.
Link Posted: 1/15/2015 4:12:42 AM EDT
[#38]
Link Posted: 1/15/2015 4:13:42 AM EDT
[#39]
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Quoted:
Use 50.  It's dead nuts on (within 2") from 30 yards to about 230 yards.  A 25 yard zero will have you missing high on anything smaller than beach ball on targets over the likely ranges you'll be firing at.
View Quote


Okay.

Again.

I'm not using a 25y zero.  I'm using an ACOG, which is designed for a 100m zero.
Link Posted: 1/15/2015 5:29:04 AM EDT
[#40]
A carbine firing 62 grain ammo with an ACOG calibrated for the M4 (such as the TA01NSN) will use the 300 meter mark exactly for a 25 yard/meter zero. Fine tune this when possible.

A rifle firing 62 grain ammo with an ACOG calibrated for the M16A4 (such as the Ta31RCO) will be about 1/4 an inch low at 25 yards.

If you are using a Ta31F and god knows what ammo, then I have no idea what to tell you. You need a ballistic calculator.

Remember these targets as a future reference:





Note the difference between the M4 sight in procedure and the M16 sight in procedure. The difference in velocity requires the shooter to make a 1 MOA adjustment up in elevation past the 300 meter mark on the drum for the m16 rifle to strike the silhouette center. The M4 qualification target does not require further adjustment as the lower velocity and higher arch required to fire the projectile to 300 meters puts you right in the zone for 25 meters.
Link Posted: 1/15/2015 5:46:04 AM EDT
[#41]
Using a TA33, AFAIK M4 with 62gr
Link Posted: 1/15/2015 5:58:50 AM EDT
[#42]
Before I answer, I need to know if you are on an incline adjustable treadmill or covered in baby oil.  Either will work for my specialized 25yd ACOG zero technique.

Posted Via AR15.Com Mobile
Link Posted: 1/15/2015 6:51:16 AM EDT
[#43]
I believe plain ACOGs are set for 62 grainers. And yes, if you are zeroing at 25yards or meters, you use the 300 yard mark so that it makes the Bullet drop reticle work.
 






If your zeroing with 55grainers then your bulleg drop reticle is going to be off if it's made for 62grain bullets. It'll probably be fine for battle, but it won't be good for precision work.

 
Link Posted: 1/15/2015 7:14:17 AM EDT
[#44]
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Quoted:
^ Exactly, that's what I keep reading on M4C, etc.

Those are in meters though, indoor range is yards, I'm almost positive
View Quote


A meter is 1.09 yards, so the difference is negligble at 25yds (or 100yds for that matter).  Just zero using the 300m aim point at 25yds and then tune it in when you get a chance to shoot at 100yds.
Link Posted: 1/15/2015 8:09:31 AM EDT
[#45]

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Quoted:


We zeroed initially at 33 meters (36 yards) using the 300 meter POA, that should get you close on the 100 meter POA, then confirm at 100.



That's a TA31RCO, it will probably be different for other models with different BDCs.
View Quote
This is exact the process I followed.

 





Link Posted: 1/15/2015 8:15:21 AM EDT
[#46]
Quoted:
Help me think this through.

I'll confirm down the road when I have access to 100m, but for a basic zero, do I use the 300m mark at 25y for the zero?
View Quote


Everyone is assuming it's .223, 5.56mm mil spec m4 is that true OP? Because that makes a difference. I mean your not zeroing your AK right? Or mini?
Link Posted: 1/15/2015 8:20:01 AM EDT
[#47]
Taggage
Link Posted: 1/15/2015 8:21:34 AM EDT
[#48]
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Quoted:


Right, but the entire BDC is screwed up if the designed POA is not at 100
View Quote View All Quotes
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Quoted:
Quoted:
Quoted:
Quoted:
50 work bedder.

http://i49.tinypic.com/15n9742.jpg


You miss the part about this being an ACOG?

Aimpoint is zero'd at 50.


I made my charts to decide if 50 was better then 100 or 75 for a red dot. I like 75 best.


Right, but the entire BDC is screwed up if the designed POA is not at 100


Nope
Link Posted: 1/15/2015 8:21:58 AM EDT
[#49]
OST
Link Posted: 1/15/2015 8:23:06 AM EDT
[#50]
OP, why ask in GD when we have an AR optics section. THIS is what you seek.


Jim
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