I recently aquired an ACOG TA31F.  I have not been able to zero the optic. It was far too windy to zero on my first trip to the range with the ACOG, so I just blasted for fun.


Last week, the weather was much better and I attempted to zero again.




First ten shot group was six inches low and three inches right. Adjusted the elevation and windage appropriately.





Second ten shot string yielded the same results. Six inches low and three inches to the right, even after adjustments were made. I would think that I would have atleast been closer to hitting my point of aim, but nothing of the sort resulted.





I will get a picture of the target up once my camera charges.





What say ye, ARFCOM?



UPDATE:



Problem solved. I don't know what I was doing wrong, but I eventually got on paper at 50, zeroed, then went out to 100 and rezeroed.



Properly zeroed, the ACOG is an amazing piece of glass. I love it!

I would shoot at 100 the way it is suppose to be zeroed and only shoot a 3 rd group between adjustments.  Make sure your mount is tight, beyond finger tight and pushed forward in the slot.

the ACOG takes some use before the adjustments take effect. Recoil is enough to do this.

Also, it would take twice as many clicks at 50 yds not half as many.

We zero the ACOG at 25 meters using the 300 meter stadia line for point of aim point of impact. At this distance on a standard M4 zero target, 5 clicks = 1 square. I dont know what the dimensions of the squares are on the target, but I bet someone on here does know. Fine adjustments are then made at 100 meters, if there is a suitable range available to do this. I say this because when deployed forward, its not always available where we may stage from. That being said, I have succesfully employed the ACOG on numerous occassions at ranges in excess of 300 meters off of the 25 meter zero.

Did you smack it with a mallet?

Tag for future reference.

Sorry can't help you there, i zero them at 100. And if your adjustment are not working, the acog might be damage. Send it back to Triji and they will repair it.

I know in the past, some people have mess with them and gone too far one way and screw them up.

That could be the case. I bought it second hand.



 

I would send it in. I got a great deal on a TA31 ($650 on the EE). I sent it to Trijicon and they replaced the cracked fiber-optic housing and the windage/elevation adjuster knobs for free (had it back in a few days). They also cleaned it out, calibrated the parallax, and replaced the adjuster springs and spring guides (this is coming from the invoice they sent back).

Thus, you know it will work once you get it back.

Half the distance= twice the clicks, not the other way around.

BTW, ACOGS need to be jolted around for the adjustments to work??  

Yes, they need a good smack on the top or side to seat the prism. When I've done my adjustments, I give it a good hit on the top and size with the base of my hand, then fired 5-10 shots to fully seat the prisms. Then I shoot my next group and make adjustments from there.

They are designed that way, it's a function of the prism housing.  One of the reasons they hold zero so well.

If anything, TAP it with a screwdriver handle. Dont beat the shit out of it with a hammer like u r pissed at it.

Correct, ACOG's use the recoil of the rifle to seat the prism.  Tapping on the housing just speeds up the process.

+1 on that. It took me awhile to figure that out on my TA31RCO-M4. It's right there in the maual. I just didn't read it before taking it out to the range. Also 1/2 distance=double the clicks. That's also in the manual.