Cannot Sight In Acog, Tried Bore Sighter


June 13, 2011, 02:46 AM
I am having some major issues trying to sight in my Acog scope. I'm not sure if the adjustments are broken, but I tried using my Bushnell laser bore sighter and adjusting the windage and elevation, but no matter how many clicks I adjusted the knobs the reticle's position would not change or move towards the red dot. Also, I have been having a major problem trying to adjust this sight at the range, as no matter how man adjustments I make it seems to lose zero.

I will admit it has been a long time since I have done any scoped rifle shooting, as I have used irons more often than not. I'm not sure if it is my crappy shooting and also that I don't know how to sue the bore sighter, but I am thinking something is wrong. The stupid bore sighter's battery seems to die in within 2 minutes, so now I think I will just have to take this thing to the range to confirm. I'm wondering if my Acog TA33R-8 is having some type of issue with the adjustments. Is there any possibility that the adjustments may be broken or am I doing something utterly stupid? I will say that I had to return this Acog to Trijicon once already because the reticle was crooked. I am truly wondering if I have acquired a lemon.

Also, I'd appreciate any advice on the best methods for sighting in an Acog using a LaRue mount on a quad-rail flattop AR-15. I have an LMR MRP CQB 16 rifle with which I am using the Acog scope. Considering, I'm not the best shooter out there, I am thinking of getting some type of rifle rest. I know a Sporting Goods store here sellings the sandbag type rests that have front and back rest and are shaped in a way to support holding a rifle. I'd be interested if anyone can give me a tips on shooting rests that would guarantee the most stability of the rifle. I just want to make 100% sure that the reason for any bad grouping is because of me, rather than a defective scope , mount or rifle.

I am starting to wonder if the prism inside the scope is broken. This perhaps could have happen from me overadjusting it or it could have always have been a defect from the manufacturer. I'm not sure, but does anyone know what ramifications I may incur if the scope needs to go back to Trijicon to repair the prism? I'm not exactly sure if this is my fault or not. Another issue I see is that the adjustment knobs are a bit chewed up. I'm not sure how this happened, but I only gently used a screwdriver tip to adjust the clicks, but the adjustment knobs seem to have eroded away.

I'm starting to get fed up with this Trijicon and thinking maybe its time I get a different scope. Considering, how much I paid for it, I am hoping I can fix it and make up for my losses. It would be nice if I could actually get this scope to work, but right now I am baffled.

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Andrew Wyatt
June 13, 2011, 10:38 AM
I would send it back to trijicon before you try anything else.

what do the groups look like, and do you have another scope or irons to shoot a group with?

June 13, 2011, 10:43 AM
Nothing is perfect. ACOGs tend to be the single most durable and dependable Optic made, but event hey can have a bad one every once and a while. Call them. They will fix it.

June 13, 2011, 11:54 AM
I've seen this happen before. Using the bore sighter, you try to adjust the reticle, but it doesn't seem to move. Then, when you get to the range, you shoot, adjust, then notice that it didn't hit where you thought it should and adjust again, then it looks like you adjusted too much. It can have you tearing your hair out.

Although ACOGs are probably some of the toughest sights on the planet, they do have their quirks. I've seen plenty that kind of have sticky internals. When you make an adjustment, the adjustment appears to not have any effect. What may be happening is that the scope needs to be jarred for the adjustments to take effect. Two or three shots should do it. So, make an adjustment and fire at least three rounds to "jar" the scope, then fire another to confirm your point of impact. What I usually do is to tap the turret that I just adjusted with the handle of a screw driver, just to give it a nudge. The upside is that once you have it zeroed, you'll never have to mess with it again.

If this doesn't help, you may have a real problem, which Trijicon should take care of pretty quickly.

June 13, 2011, 03:26 PM
I am sending this scope back to Trijicon. FOr all I know, I damaged the scope trying to get the thing zeroed. I know that I hit a notch where there was resistance and attempted to adjust it more. The only reason I got so frantic is that no matter how much I tried to adjust and tap the turret it would not move the reticle. I suppose a trip to the range may have remedied this as some said. However, I have taken this scope to the range on several occasions and have had lot of issues with achieving zero. Maybe, it is my lack of understanding of this scope. However, I will say this Acog was a lemon out of the box and came to me with a crooked reticle which I had to send to Trijicon (at my own expense) and which they remedied and sent back to me (at their expense).

June 13, 2011, 04:15 PM
It may be bad from the factory.

I doubt you broke it by adjusting it all the way to it's stops. 1,272,893 Marines, Soldiers, and Airmen have done the same thing or worse with thier ACOGS.

Marines can break anything.

Make sure your mounting screws are tight. Larue is a darn good mount so I doubt it's the mount shifting or anything. Most Larue mounts can't be mounted wrong, the tabs on the bottom prevent it.

But when you latch it on, right before you tighten the QR lever, shove the mount forward with a little pressure so that the mount is all the way forward pressed against the rail lug.

How far away was your target you were zeroing on? Was it up/down or left/right you were haveing trouble with.

I use a Laserlyte Lt150 to sight in at 25. I just make sure I'm centered left/right. No point in zeroing elevation at such a short range. I should be 2-3" low at 25y. Then I move the target out to 50 and shoot a mansized target, then to 100.

June 13, 2011, 04:42 PM
Before you sed back any part you consider "broken" consider one thing that I discoverd the hard way. There is nothing wrong with your rifle mount or scope, your scope is mounted TOO HIGH for your bore sighter to work properly. This happened to me before I found out Brownell's sells a gadget that raises the boresight arbor up high enough to zero in your rifle. Also I found the same problem zeroing in my scoped M1A. Now I use a laser boresighter that fits directly into the rifles chamber. Try it, it works!

June 13, 2011, 05:42 PM
I already sent the Return Authorization to Trijicon's website. If there is nothing wrong with the scope, at least I can hear it from them. I agree there are so many things I probably done wrong. I do have a laser bore sighter that goes in the muzzle. As far as the mount being too high, that is a possibility, but my problem is that the reticle would not adjust at all, no matter how many times I adjusted the clicks. I also shaved away a good amount of the brass on the turret notches, so if nothing else, I would like it if Trijicon could replace those. Therefore, I don't think I have a lot to lose, except some shipping, by sending it to them.

Zerodefect, I am happy to hear that you don't think I broke it. I did turn the elevation all the way down and kept it going a few clicks even after I felt some resistance. I wasn't so sure how fragile the prism was, but I heard of people messing their Acog prism's up doing that. Anyway, I'm hoping I didn't do any damage, that may not have already existed with this scope. Just to be safe, I think I will send it back anyway to have it examined. This scope has been such a pain in the a** for me, right from the beginning. IT came from the factory with a crooked reticle and it never seemed completely right to me. I know it had zero when it came to me after the factory, but after a few trips to the range, it was shooting all over the place.

I understand I have a lot to learn about this Acog scope. To me, it seems like a scope if I could just get the hang of it. However, it seems pathetic that I am more accurate with irons then my Acog. It could possibly be that I am sighting in too far away. When I get my Acog back I will try sighting it in at 25 yards first and go from there.

As far as the boresighter distance, I was in my garage and didn't have any options with distance. I will try laser boresighting it in the range. My Bushnell boresighter seems to lose its laser light within 2 minutes. I will try to find the Laserlyte boresighter. Is that a chamber boresighter or one that goes in the muzzle end? I might also look into any other gadgets or gizmos that can assist in boresighting.

I definitely could use some assistance with sighting in my rifles. I've gone through so much dang ammo trying to sight in my scopes (especially this bloody Acog), that it is just isn't worth it. Maybe, I should just stick to irons.. LOL

I do have a big 8-25 Nightforce scope that is mounted on my LR-308 which is just a safe queen. I wonder what would make a more effective training tool, the Nightforce or Acog? I've put my .308 away because I don't have anymore money to shoot the match grade .308 ammo this 24" SS BB gun requires. It's kind of sad just seeing that Nightforce sitting on that scope, however I feel the scope is bit overkill for an AR-15, where I would only be shooting 50-300 yards anyway. Anyway, I would like my ACog to work, I did fork out a lot of money for it.

Andrew Wyatt
June 13, 2011, 06:17 PM
sight it in at 100. that's where the reticle is set up to work.

June 13, 2011, 06:31 PM
man, never use force on glass, plastic or electronics! they can't take it, and that is that. you will be lucky if Trijicon doesn't use your "shaving' of the mounts as an excuse to not fix things under warranty. Any non-gun oriented company would do so in a heartbeat, especially an electronics outfit.

June 13, 2011, 06:56 PM
Okay, I'll give you a hand here. I was an SDM instructor in the army, and we used the ACOG on the issue M4's out to 600m (you could go farther, but it was a crapshoot as to whether or not you could hit the iron sillhouette). This will work for just about any scope, but this method works very well for the ACOG given that it is ballistically co-designed with the M855 ball and carbine barrel in mind, and that it has the main stadia at 100m.

Before starting, make sure everything is tight. The barrel doesn't wiggle, the scope is tightly screwed to the base/mount (blue loctite is a good idea too, a very good idea) and the base/mount tightly locked to the rifle. If it has screw knobs, using loctite on these is good too, in addition to marking the knob and rifle with a marker so that if it comes loose, you will see the marks not line up. I messed up one time and tried to zero a rifle in which I forgot to tighten the mount down. Needless to say, it didn't work, and I felt like an idiot when I got home after wasting 100 excellent handloads. But it couldn't possibly be "me" that screwed up, it had to be the rifle, right? Double check everything.

Start by taking the ACOG and turning the dials, vert. and horiz., all the way until it stops in one direction. Then turn it all the way back, counting the clicks. Finally, turn each knob halfway back. Now you have the reticle "zeroed to the scope" meaning that the knobs are centered halfway between the limits.

Now get in the prone and shoot at a target only 25m away. Just to get on paper, don't waste much ammo here. Don't worry about hitting center either. Just try to hit a piece of notebook paper.

Now set up your target at 100m. Get in a good prone position (or benchrest) and fire two or three rounds (you can fire only one if you want/plan on more adjustment at farther ranges). You should be on paper here too. Measure your distance from the center of the target to the center of the group. Say it is 6 inches left, vertically it is fine.

Go back to the scope and adjust 6 inches right. Each click is 1/4moa, or about 1/4" at 100m. So turn it 24 clicks to the right. Fire two or three more rounds. You should be about or on the center of the target.

Now you can fire groups of three-five to fine tune the adjustment if you like.

If you go out to a greater distance, you may find it necessary to further fine tune the zero for more accurate shots as you collect data, but the idea of the ACOG is a 100m zero with M855 ball ammo fired from a military M4 will be zeroed at the other ranges by virtue of the known ballistics of this particular setup. Using the TA01NSN on issue M4's this was the case. It may be a little off using different weight bullets, barrel lengths, or rates of twist. When using M193 ball, the trajectory was off enough at distance to make a difference.

Try this to zero your rifle when you get it back. You will get the best results with the ACOG at various ranges if you use the M855 ball, or similar weight bullet loaded to similar velocities.

June 13, 2011, 06:56 PM
I am prepared to pay to fix the thing.. I agree I probably screwed it up.. I am thinking I am at fault here, but I am hoping Trijicon is honest enough to admit if there was something wrong with the scope that was not related to what I did. As I said before, the scope arrived to me the first time with a crooked reticle. I will see if there is any damage and how much it would cost to fix it.

June 13, 2011, 08:35 PM
Thanks for your advice Strykervet.. I will certainly follow the sighting in procedure you listed once I get my scope back. It sounds to me like the best way to go about it. Sometimes when I sight in, starting from too far away, its take me too long to acquire shots on paper. Still waiting for my Trijicon Return Authorization No..:uhoh: I will admit I feel really stupid right now about this whole thing.. However, who knows, it can be a defect.. This scope has not been without some issues, like I said.

June 13, 2011, 08:54 PM
Whenever I mount a new optic on an AR, I simply press out the rear take down pin, remove the bolt carrier, bolt and charging handle, look down the bore and align the barrel to a target 25 yards away. Then I adjust the reticle or dot to the same target, constantly checking that the barrel is still on target. Once I've done that, I reinstall the charging handle and BCG and fire a couple of rounds at the target to see if I'm close. The rest is just fine tuning. I did this last week when I mounted a new Aimpoint M4s on my POF using a LaRue LT659-NV QD mount.

June 13, 2011, 09:32 PM
Whenever I adjust an ACOG, I give it a few taps every time I switch anything. Works like a charm.

June 13, 2011, 09:45 PM
I lied. I have the Site-lite bore laser. It allmost allway gets me on a sheet of notebook paper at 50y. Great for pistol sight installs.

I just open the back door of my house and point my rifle at the side of my truck at an angle noone outside can see me. Usually 20-30yards or so.

I only use it to make sure my scope cross hairs are level, need a vice and bubble or laser level for that; and to make sure my scope is centered left/right.
Never for up and down since my scope is 3" high, obviously at short ranges I won't be able to get my scope down.

Trijicon is an honest co. If it's a defect they'll cover it. If you broke it they may still cover it. If you got really crazy and damaged an expensive part they may repair it for a quite resonable fee.

They obviously see way more interestingly broken ACOGs then what you could have possibly done so I wouldn't sweat it. It's not like you ran it over with a tank, shot a hole through it, filled it with #2 diesel fuel, or cleaned the lense with a concrete rock. Trijicons biggest customer has done all of those.

June 18, 2011, 03:44 PM
I know how you feel..internal concern. just purchased acog usmc 4x32,,could not laser bore sight it in ,,knobs were not responding to any change laser dot.. tried taping on adjustments after each click,,nothing.. called trijicon and got auth for return. was gone 2 weeks, got it back 3 days ago and all is well. invoice states,, internal adjustments,,,N/C. had even taken it to range thinking a few rounds through the wilson combat it's mounted on would free up prism. no luck,, both the windage and elevation knobs were unresponsive.. cost 41 dollars to send back through usps, the local dealer paid my cost to ship back.. was hopeing they would just send me another scope since it was brand new but trijicon repaired it. yes and I read the owners manual where it states that overextending the adjustments could cause internal damage my adjustment knobs were extremely hard to turn the first day I tried to laser sight it..this usmc-rco was on a shelf at dealer where people could open glass cabinet and handle the scopes...only thing I can think of is someone was messing with it ,,and tightened the windage and elevation knobs beyound the limits. trijicon was on top of it, got it back to me within 2 weeks

June 18, 2011, 08:56 PM
The only thing I can add to the advice already given is that Trijicon recommends a solid "whack" with the palm of your hand to the optic to seat the adjustments. Not just a "tap". Worked fine for me.

+1 on just pulling the BCG and bore sighting with the bore at 25 yds to get on paper. Just stabilize the rifle with some sandbags or a back pack stuffed with clothing.

Remember, when moving the reticle to the target, the adjustments are opposite of the markings which are referenced to "moving" the point of impact. IE, if you look through the barrel at the centered target and then when you look through the scope you need to move the reticle "left" you turn the adjustment knob in the direction labeled "right".

June 20, 2011, 01:20 PM
Horton, it sounds like me and you have had the exact same issue. Perhaps, there really is some issue with my Acog. Anyhow, my Acog is in transit to Trijicon and I will just have to wait to see what happens. At least, after Trijicon fixes it or tells me that everything is working, I will have no excuse not to be able to zero it in at the range. I purchased an adjustable front rifle rest along with a fixed rear leather rifle rest for my AR. This should make sighting in my Acog easier. I'll just pray and hope that I can get this working right when I get my Acog back.

I'm assuming if you are sighting the rifle in at the range, that the recoil of the rifle should give the scope enough of a jolt to avoid having to "whack" it. I don't know, but I hate whacking things that cost over $1000. :uhoh:

June 20, 2011, 02:15 PM
Trust me, the ACOG can take it.

June 20, 2011, 10:08 PM
yes, got my acog back and took it to the range sunday,, flawless,, will shoot 1 inch groups at 100 yards,,on bipod,,, it's mounted to a wilson combat tactical rifle. adjustments went flawless. very impressed with this scope for a fixed 4 power. *** was wrong with it before I sent it back,,don't know,,invoice from trijicon just states-internal adjustments- warranty-no charge.,,,

June 20, 2011, 10:22 PM
and evergreen,,all i did was tap on the adjustments with my knuckle after each adjustment. only had about 12 clicks from zero for elevation at 100 yards and about 5 on windage knob for zero at 100 yards...... before I sent it back to trijicom couldn't get the dam adjusters to move at all,, also the adjusters are nics and easy to turn,,before tighter than hell from the time I mounted on my rifle and all adjusters were super hard to turn, from the get go.,,,I was really wishing I hadn't purchased the 1500 scope...till I got it I'm glad ,,,love the thing..good luck ,,trijicon will make it right don't sweat it..I READ YOUR POST AND KNEW WE WERE BOTH HAVING THE EXACT ISSUE.

July 2, 2011, 05:51 PM
evergreen, you should have got your acog back by now, everything good?

July 5, 2011, 12:39 AM
It is a bit more work with an AR but you can break down your upper, remove the bolt, then bag the barrel. Look down bore from breach at a target and center the bore on the target.

W/O disturbing the upper, look though your optics and see if your aiming point is on the target, if not, adjust elevation and windage. Double check that your bore is still aligned to target, repeat if necessary.

Put rifle back together and shoot at target for fine tuning.

Bolt action rifles are a lot easier :)


December 28, 2011, 11:42 PM
New guy here and searching through I found this, yeah my "new to me" IE USED HARD acog did the same thing, I sent it back to Trijicon last week and they told me what I already assumed, the guy before me dialed the thing around so much that the prism broke inside. Waiting on word of cost.


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