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Posted: 7/15/2026 5:38:33 PM EDT
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I bought a new one a year or so ago from Euro Optics per y'alls suggestion not to buy one from Amazon. Mounted it on a Colt LE6920 that has a 11.5" Colt police trade in upper on. Barrel looks great inside. Used my trusty SiteLite to sight it in that I've been using for years. Took it to the range, and couldn't hit paper at 50 yards. Got pissed and put it in the safe and forgot about it till around 6 months ago. Bought one of those 5.56 laser bullets and sighted it in with that, same results. Back in the safe it went. Couple days ago I taped a piece of paper with a orange dot printed on it to my across the street neighbors garage door. Clamped the upper in a drill press vice and moved the upper till I could see the orange dot thru the barrel, the adjusted the ACOG to the dot. Went to the range today, and same damn results. Due to the heat I was the only one there, and asked the range master if he wanted to try it. He had the same results. I used the orange dot to sight in my Vortex on my 5.56 bolt action rifle, and it was a click or 2 from being perfect. Is it possible I got a bad Trijicon? I've got 7 AR's but other than a 7" pistol the Colt is the only one without a carry handle.  
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Even though it was way off the POA, did it still shoot close groups, or I guess did you even try that? Does the reticle actually move as you'd expect when you bore sighted it or do they seem bound up? Did you perform the factory mandated hammering on the turret erectors after each adjustment? 
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| I mean yeah it’s obviously not mechanically zeroed close to your bore, but did you try shooting at 10-25 yds to see where it’s actually at? Then you can walk it in and try zeroing and see if it holds zero. As long as you’re not at the very edge of adjustment it really isn’t a big deal. |
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Originally Posted By D_Man: Even though it was way off the POA, did it still shoot close groups, or I guess did you even try that? Does the reticle actually move as you'd expect when you bore sighted it or do they seem bound up? Did you perform the factory mandated hammering on the turret erectors after each adjustment? |
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You could have made more of an effort to see how much it's off. What size "paper" were you using? Did you try aiming high, low, left and right to see if you could hit paper? Did you try a shorter distance? Did you try a bigger/multiple pieces of "paper?" Do you always give up so easily when something doesn't work the way you expect it to? Trijicon has great customer service, and they'll probably take it back, but I don't understand why you wouldn't make more of an effort to diagnose the problem. |
Posterity! You will never know, how much it cost the present Generation, to preserve your Freedom! I hope you will make a good Use of it. If you do not, I shall repent in Heaven, that I ever took half the Pains to preserve it.---John Adams
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Rough zero at 7 yards. This will get you on paper. Dial in your windage, and set your elevation so you’re hitting 2.5-3” low. It should take 2-3 shots. Then walk it out and you should be on paper for fine adjustments. I have the displeasure of owning a Mantis. It’s an eye opener as “zeroing” the laser gets significantly harder the longer the barrel is. This is a good sign that the laser isn’t very precise. Unless the laser is the exact diameter of your bore, at the bore, there’s a very good amount of error there. |
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Originally Posted By intheburbs: You could have made more of an effort to see how much it's off. What size "paper" were you using? Did you try aiming high, low, left and right to see if you could hit paper? Did you try a shorter distance? Did you try a bigger/multiple pieces of "paper?" Do you always give up so easily when something doesn't work the way you expect it to? Trijicon has great customer service, and they'll probably take it back, but I don't understand why you wouldn't make more of an effort to diagnose the problem. I was using 12x18 inch - Silhouette Splatter Targets. Range only has 25, 50, and 100 yard spots for rifles. I shot at 25 yards today. I aimed high, low, left and right. When the range dude was shooting it, it looked like concrete dust was coming off the top backstop. Maxed out the adjustment both ways and same thing. Shame I didn't have a 5x5 foot piece of cardboard to put on the target stand. What the hell is this? "Did you perform the factory mandated hammering on the turret erectors after each adjustment?" |
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Laser bore sights are dogshit. Pull your bolt and bag the upper so it's stable, then line up the target looking through the barrel at 100. Then without moving the upper, adjust the ACOG to the target. Look back and forth barrel to optic until it looks good. For live fire, start at 25, adjust, move to 100. You want to be maybe an inch or so low at 25 |
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Originally Posted By D_Man: You need to smack the turrets after adjustment, it's in the manual: https://www.ar15.com/media/mediaFiles/157876/tapped-3183990.jpg I'll be damned. I never felt the need to read the manual. When it says light tap, exactly how light? Tap it with a spent round or smack it with a loaded mag? I'll have to try it out tomorrow. |
Just like this? Sighting in your acog |
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Ah the joys of getting ACOGs sighted. I’ve got 6 of them with a brand new 7th needing to be sighted in. I bring a mini Snap-On flathead screwdriver and tap the turrets after each adjustment. I’ve had some that don’t need the tapping at all and some that needed it after every click adjustment. I’ve had to send a new ACOG or two back. It’s always past my return window when I can get the new ones zeroed at the range, which sucks. Once they’re set though… absolutely bombproof. It almost sounds like your mount/mounting is jacked up, or a bad ACOG. I’ve never had one with your exact problem. I had one run out of adjustment room but I was on paper - that one sucked - almost threw it downrange. Sent it in and got it back fixed. |
Joined:
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I never smacked the turrets on mine. Make sure the mount is tight to both the optic and the rail. Get a big piece of cardboard; the side of any good size box will work, put a sharpie dot in the center, and shoot a three round group at it from 25 yd. You should be able to hit that with no sights at all. You'll hit it somewhere; start making adjustments and walking it out till you're zeroed at 100. If it doesn't shoot a "group" at 25, change to a different optic and try again. If it repeats, look hard at the gun and ammo. The info so far in the thread doesn't yet point at any specific part of the system as being the problem. |
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Originally Posted By wood714: I'll be damned. I never felt the need to read the manual. When it says light tap, exactly how light? Tap it with a spent round or smack it with a loaded mag? I'll have to try it out tomorrow. ).You should also check the mounting screws in the base of the mount itself. Pull them out clean them off if they have a thread locker on them and reapply loctite and tighten them evenly. |
What it boils down to is that they fear an effective resistance to their power: So, Left in power=Guns bad, mmmmkay...?, Right in power=Guns good!-thskirk
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Originally Posted By Alaskanforfreedom: Smack it with your hand. Im surpriaed the range instructor didnt think of it. Also if youre using your hands to tighten the factory mount that could be your problem. I like to hand tighten then go an extra little bit past that with a quarter or a butter knife (or screw driver ).You should also check the mounting screws in the base of the mount itself. Pull them out clean them off if they have a thread locker on them and reapply loctite and tighten them evenly. When I mounted it, I went hand tight then a 1/4 turn. The mount is solid as a rock. Sent Trijicon and email about it. |
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Originally Posted By Brahmzy: Let us know how this works out.. I emailed Trijicon, and they said send it back. Then I thought even thou the directions that came with mine didn't say anything about smacking the shit out of it, I rezeroed it with the orange dot I taped on my across the street neighbors garage door, and then put the 5.56 laser bullet in it, and adjusted the green dot right on top of the red laser dot. Tapped it a few times with a screwdriver handle. Went to the range and traded them a couple of my 12x18 targets for a bit larger one. The 25 yard range was taken so I shot at 50 yards. First shot was on paper. I was most happy. After 5 adjustments tapping them with a mag each time, I got pretty much center. As good as I could do resting the hand guard on my range bag as best as I could. After seeing how good it shot, I did a 18 round mag dump in the middle. I'm really happy with it now, but the old Colt LE6920 trigger leaves a lot to be desired. Thanks to everyone who posted in my thread, much appreciated!  
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