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Posted: 10/22/2003 11:21:19 AM EDT

I had some problems zeroing in an ACOG TA01 Scope while mounted on a flattop 16" rifle. Trijicon mentioned to me that the TA01 is calibrated to be mounted on a carry handle, not a flattop.

I was looking for some additional input from you guys about this. Anybody got this mounted on a flattop okay?
Link Posted: 10/22/2003 12:24:57 PM EDT
Lots of people mount them on flattops with no problem. You say you are having a problem - well what kind of problem? Range you are trying to zero at? Which line on the reticule are you using? Ammo?
Link Posted: 10/22/2003 3:58:31 PM EDT
I have the rifle zeroed in at 25 meters using the iron sights and it is perfect there. But when I attempt to zero the ACOG at 25 meters (when rail mounted on the flattop), it is off paper (I run out of scope adjustment clicks). I sent the scope back to Trijicon and they recentered it and said that the TA01 is only calibrated for attachment to carry handle. I also found this on their website for ACOG FAQ: What bullet was used to calibrate the ACOG scopes? The TA01, TA11, & TA31 (.223) was desinged for the 5.56mm, 20 inch barrel, 55 grain bullet, M16/AR15 carry handle mount. The TA01B & TA11C(.308) was desinged for the 7.62mm, 20 inch barrel, 168 grain bullet, M16/AR15 carry handle mount. The TA01NSN was designed specifically for the US Special Operations Command SOPMOD M4 Carbine. To meet their requirements, the reticle bullet drop compensator and range finding stadia lines are based on the trajectory of the 62 grain bullet from a 16 inch barrel, flattop mount (Picatinny rail Mil.Std.1913). So, this begs the question... Do I need the TA01NSN for a flattop 16"? If anyone has the TA01 mounted on a flattop, I'd like to hear your experience.
Link Posted: 10/22/2003 6:27:10 PM EDT
If you try to zero it at 25 yards, you are going to have all kinds of problems no doubt. You'll be on at that point but so high at almost any other distance. Thats not really the way the optic works. I had a TAO1 on a flat top and it works fine if you zero it correctly and then learn where it shoots at given distances. With your optic, your rifle and mounting system, do this... For a Flattop 16" firing M193: Sight in 1" high at 100m. You'll be 0.3" high at 200, 0.7" low at 300 and within MOA until 600 where you will be 10" low. This info is available at Bartholomew_Roberts most excellent [url=http://www.ar15.com/forums/topic.html?b=3&f=18&t=152794]"Big ACOG BDC Chart"[/url] thread tacked to the top of the forum. You're going to be shooting low at 25, but so long as you know that and compensate for it, you will be able to know where you will hit at ranges from arms reach all the way out to nearly 600 yards! This is sort of what we mean when we say ACOGs take a little time to get used to and learn to use. But once you do you are almost unlimited in what you can do with them.
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