Not able to zero Trijicon TA11F ACOG

[HURLEYGO3]

I just picked up a new Sig 556 and a put a Trijicon TA11F ACOG on top of it. Went out to the range and was able to zero it in. I ran out of adjustment and it is still about 5in low at 100 meters. It is mounted with a Larue LT100. Is it me or the mount? Where should I start?

[Ripper]

Sighting TA31F

Hi I have the same set up except my ACOG IS a TA31 RCO M4 made for a 16in barrel.you TA31F IS NO DIFFERENT I could not zero MINE at first. I bought a laser bore sight / Sight Mark brand. It is the one that fits into the chamber. I went to 50yard range to start and turned my elevation and windage and lined it up on the laser dot. I have the cheveron type reticle, remember that at 50 yards your poa or POI is at the bottom of the tip of the cheveron just under the "V". Then take a few shots with out the laser in the chamber of course, You should be on Paper at 50 yards. Make your adjustments so that you shots are at the bottom of the tip of the Cheveron this is your 50 yard zero. Then put your target at 100 yards. You 100 yard zero is the (TIP of the cheveron) adjust the ACOG TO where your hits are at the tip. You should be able to adjust it. MAke sure that your rail is tight and not loose. Then remount your ACOG make sure that you push down and forward on the scope then tighten your levers. I am hitting dead center at 100 yards give or take 1in. Remember these SIGS are Carbines and not sniper rifles. The best group you will get is 1 to 2 inches. Mine shoots well with 62 grain PRIVI AMMO. If you shoot M193 55 grain ammo your hit will be low. Try the 62 grain stuff. you will see a difference. Hope this helps. Get back to me on your progress. Thanks Ripper

[HURLEYGO3]

thanks for the reply. i will let you know what i find.

[NSR500]

How did your gun shoot at 100 meters before you put the ACOG on? Just makes me wonder if you barrel is straight.
My buddy had an AR15 that was at the maximum of adjustments with it's mechanical sight. Obviously, when he put on an Aimpoint it was nearly maxed out as well.
We tried the Aimpoint on my rifle and it was fine with plenty of adjustment. So, he sent his rifle back and they replaced his barrel. The gun shoots great now and has a lot of headroom with both mechanical and optical sights.
Try the ACOG and Larue mount on another rifle to see if they work, otherwise it might be your gun.

[eric1972]

Try from a closer range first, e.g., 25 yards, and then move further. That should give you an idea of what the problem may be, e.g., the barrel, the scope, mount, etc.

[gimmejr]

Took some adjusting to get my acog zeroed, Id try it without the larue mount.

[HURLEYGO3]

Someone also pointed out the they had problems with the clearance on the mounting bolts on the sig rail.