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1/16/2020 9:48:49 PM
Posted: 11/17/2012 12:41:40 PM EST
[Last Edit: 11/20/2012 4:17:13 AM EST by Indrid_Cold]
Well folks, I am coming here because I'm truly stumped and I humbly ask for your assistance and advice. A bit of background first in case any of it is important for diagnosing today's issue...

About six years ago, I was finally able to buy myself a rifle - an AR-10 with a National Match barrel - after years of having shot a Ruger .22 that my dad purchased for me when I was 11. I had done a bunch of reading online (here and elsewhere) about different platforms and settled on the AR-10 after some weighing of the pros and cons. I didn't make any major changes to it, but I did add an ARMS slimline (.mil version) rifle length handguard, a Command Arms ARS stock, and switched out the grips as well. So, some upgrades, but didn't really do anything to the functional insides of the rifle. I had saved up some money for nice glass and got an ACOG 5.5x50.

Unfortunately, my college years took me away from my rifle and I didn't get a real chance to sit down and sight in my ACOG at a proper range. At some point during then and now, I had the gas tube replaced (it got chipped - long story), and realized that for whatever reason, my ACOG's point of impact was very off. No worries - I sent it back to Trijicon, and they gladly reset it to factory zero for no charge. That was fairly recently, and I just got a chance to take out my rifle to the range today in hopes of zeroing the sucker in once and for all. Remember, at this point the rail has now been taken off/put back on (to change the gas tube) and the ACOG has been back to the factory once for adjustments.

Well, there I am today starting at 50y just to see where we are on the target, and we are way, way off. Like, not-even-funny off - almost not even on the target - and I'm having a hard time even figuring out where the rounds are striking in order to address how I should start sighting in the ACOG. Then I noticed that the target seemed a little blurry. I took a look at one of the targets at 100y and saw that it was even blurrier - so much so that I almost couldn't see it.

So here's where I stand - I really don't know what's so wrong with my rifle that it's not even putting rounds on target at 50y, but I do know that it's embarrassing. I don't know if it's the ACOG, or the rifle, or both. I have built a number of AR's since purchasing my AR-10, and they've turned out just fine as far as accuracy is concerned, so I don't think I messed something up with the AR-10 when I haven't even changed any of the internals. I'm a good shot with other firearms so I don't think I have a glaring issue with my own abilities.

What could I be doing wrong?
What hardware issues could I be having?
What should I do to test what the problem(s) is/are?

Any and all advice is appreciated - I'm at a loss and I just need some help.



UPDATE 11/20 - I removed my ACOG from my rifle and was getting ready to box it up when I noticed that there was a significant amount of movement between that front "section" or "shroud" of the ACOG and the body itself... Not sure what on earth could have caused that, but given that a lens is housed in that section, I'm sure that's significantly contributing to (if not causing) my woes. RMA submitted today, so hopefully I'll ship my baby out soon
Link Posted: 11/17/2012 12:44:25 PM EST
Someone much smarter than me will chime in shortly. Sounds like something is wrong with your ACOG if it is blurry though. I am guessing you've already cleaned the lens and it is still blurry?

Move in from 50 yards. If you are not even on paper at 50yds you are just wasting ammo. Move in to 25 yards and shoot prone to get on paper. Adjust to get zero at 25 yards and then move out to 50 yards. You shouldn't be to far off at 50yds with a 25yd zero.
Link Posted: 11/17/2012 12:49:36 PM EST
Sorry for forgetting that part earlier. Yes, to clarify - the glass is absolutely spotless. The beams at the range today (at ~15-20y) were crystal clear.
Link Posted: 11/17/2012 1:30:18 PM EST
What model ACOG do you have? Why are you mounting it on the handguard instead of the upper?

Always begin a new sight in at 50 feet or closer.
Link Posted: 11/17/2012 1:44:26 PM EST
TA55A

Picture to clarify the mounting situation - the top half of the rail system extends over the AR-10 upper as part of the mounting process.


Link Posted: 11/17/2012 6:44:32 PM EST
[Last Edit: 11/17/2012 6:49:22 PM EST by MatthewCourtney]
That ACOG has no diopter adjustment. You probably have an astigmatism or other vision issue that requires diopter adjustment for a clear image at varying ranges. Make an appointment to see an opthamologist and bring the scope with you.
Link Posted: 11/17/2012 7:34:17 PM EST
[Last Edit: 11/17/2012 7:35:09 PM EST by Bizzarolibe]
Originally Posted By Indrid_Cold:
TA55A

Picture to clarify the mounting situation - the top half of the rail system extends over the AR-10 upper as part of the mounting process.



I'm not at all a fan of that mounting system you've got going on. That could very well be the problem. Have you tried shooting it with other optics to rule out the mount system as a possible problem?
Link Posted: 11/17/2012 8:36:00 PM EST
[Last Edit: 11/17/2012 8:42:47 PM EST by bloodsport2885]
What's the eye relief on that specific model? Is the stock at the position you use to shoot?

I'd swear that eye relief was too much for pretty much any scope.

ETA Trijicon lists that model has having a 2.2" eye relief. Your eye is about 4 inches too far from the scope.

ETA 2 - 2.2" of eye relief might be enough to ruin your day in a .308. Who thought up this scope?
Link Posted: 11/18/2012 3:33:43 AM EST
Then I noticed that the target seemed a little blurry. I took a look at one of the targets at 100y and saw that it was even blurrier - so much so that I almost couldn't see it.


Have another person look through the scope and see if the are getting a blurred image. It could be a bad scope.
Link Posted: 11/18/2012 4:51:14 AM EST
Lot's of good advice here.

On every scope I mount I first check at 20m. I shoot from sitting on the ground and fire one shot. This should be somewhere on the 18"x24" target paper. I then make rough adjustments and set the rifle up to be near "on" at 100m {20m POI varies between sighting systems}, then I move to 100m and continue. W/ this method, frankly, I can normally go straight out to 200 and zero.

I'm not familiar with your scope. But if it sat in inventory for any length of time somebody may have monkeyed with the adjustments. Normaly scope adjustments are centered. This helps but does not guarantee a well-placed first shot.

Who knows what your problem is, but just my $.02.

Best.
Link Posted: 11/18/2012 5:35:43 AM EST
Originally Posted By madcratebuilder:
Then I noticed that the target seemed a little blurry. I took a look at one of the targets at 100y and saw that it was even blurrier - so much so that I almost couldn't see it.


Have another person look through the scope and see if the are getting a blurred image. It could be a bad scope.

This.

Link Posted: 11/18/2012 6:08:54 AM EST
[Last Edit: 11/18/2012 6:34:16 AM EST by Triumphman]
Got to look at 3 things. Make sure that rifle is unloaded first.
1: look at rifle. You need to see if that handguard isn't loose or un-supportive on the end. There's a lot of weight up there, where the Bi-pod is, if that Handguard is loose or has any flex in it. Take rifle's barrel and "Point at you". Now grab hold of barrel with one hand and Handguard with other hand, and see if Handguard moves––even the slightest. If so, that needs to be tightened down, or screws "loc-tited" if they're loose. Anything to take out slop. Do this test again when done. This also checks if barrel is loose too, and if you notice wiggle in it. If Handguard is flexing/won't tighten up, you need to change out to better/different Handguard for better support and also for Bi-pod that puts stress on barrel from the underside.
2: I like those type rails that extend out over barrel, as it clamps down onto the barrel(in this case the handguard tube), and makes everything as "one unit", if this is the type you have mounted. However I don't like the height of them in this case––-a rail on top of another rail(weak link), which in this case, sets that scope pretty high on that rifle, when you need a scope mount system that keeps things more close together. So that might need to be changed out to bring scope closer to centerline of rifle. Lots of things will not let a scope adjust correctly to rifle, and you need to find that "Weak Link" and correct it.
Here's a cheap way to try and get that rifle better on target. You need a "Lazer Bore Guide" it's lots easier. Now aim rifle/lazer to put centerline of bore on Bullseye. Once done look at scope. How far off is crosshairs? I don't look so much at Elevation, as long as it's in a straight line and slightly above Bullseye. However, I DON'T want it more than 4" over Bullseye. This can be adjusted out when you get to distance you'r shooting at.
I look to Windage, and get that lined up AND onto Bullseye. If scope just won't adjust properly you have problem with it, OR, in majority of cases your scope mounts, as you have an alignment/mounting issue with them. Don't know ACOG's adjustment range. Usually Windage won't be more than 2-4" off, if good Centerline base drilled correctly and a properly centered scope used.
3: If shooting Factory Loads, that rifle will let you know what it likes, so you need a variety of different Manufactured ammo to test with. Trust me, you'll know right immediately, which rounds it likes by it's Grouping, using a 3 shot test of each ammo. But, do it slowly, as you don't want that barrel to get hot, as that also will throw off your shots. If doing handloads, you need to play with powder charges, primers, bullet weights and bullet tip/tail differences to find what that rifle likes––-just like Factory ammo. Lots of things go into an accurate rifle than people think. Hope this helps and keep us informed of results.
Del
Link Posted: 11/18/2012 7:04:50 AM EST

Originally Posted By MatthewCourtney:
That ACOG has no diopter adjustment. You probably have an astigmatism or other vision issue that requires diopter adjustment for a clear image at varying ranges. Make an appointment to see an opthamologist and bring the scope with you.

Appreciate the idea, but I don't think it's my eyes. This scope was clear as daylight prior to sending it off to Trijicon. No other issues with other scopes either, including other ACOGs.
Link Posted: 11/18/2012 7:14:59 AM EST
Some good suggestions already and some not so good ones.

1. You want to make sure your glass is good. ABSOLUTELY NO SENSE getting the thing all set and the scope is out of focus. Have somebody else look through it at objects at various ranges. They should all be clear. If not send it back or if it's you, go see the eye doctor.

2. The mounting system. Try to get it mounted all on the upper receiver. As mentioned above when you bridge the upper and the hand guard any flex in hand guard could case a shift in POA/POI. A free float hand guard is used so that one can rest on it or on a bi-pod mounted to it and not flex the barrel. That said, if there is flex in the hand guard it doesn't mean it was installed incorrectly or anything needs to be done, only if something is actually loose. Doing what Triumph said you could very well see slight movement with a barrel that long and gun that heavy but it does not mean anything needs to be fixed.

3. sighting in - start at 25yd and then move out. One thing you have to know about ACOGs their adjustments can stick. After you make an adjustment smack the scope firmly a couple times with your palm.
Link Posted: 11/18/2012 7:19:27 AM EST
[Last Edit: 11/18/2012 7:19:49 AM EST by Slu54]
Do you have ironsights? Can you zero on ironsights? If you can, then it's probably not an issue with the rifle.

If you can zero on ironsights, put the ACOG on. Start at 10 yards, and move your way back 25 yards, 50 yards, etc. I'm quite sure you can get it on paper at 10 yards to see POI versus POA.
Link Posted: 11/18/2012 8:04:14 AM EST
Not to be the "did you turn it on?" tech support guy - but where are you holding your eye relative to the scope?

ACOGs tend to have pretty limited eye-relief, "blurry," combined with "unable to zero" almost sound like you're not placing your eye in the proper "eye box," whether because of the height of the riser without a cheekrest, or because you're simply placing your head on the wrong part of the stock.

Trijicon lists the eye relief as 2.2", i.e. your eye needs to be 2.2" away from the scope in order to get a proper sight picture.

If your eye is not in the "eye box," then you're probably also getting a hell of a lot of parallax, probably making it difficult to zero.

Besides being off target, how are your groups looking?

~Augee
Link Posted: 11/18/2012 8:09:53 AM EST
It looks like your ACOG has throw lever mounts on it. Can you lose the piece that the ACOG is attached to and place it directly on the upper receiver and see if that helps.


Sir James...
Link Posted: 11/18/2012 8:42:16 AM EST
I would try different eye relief distances and see if it clears up. The right side of the optic glass being blurry is normal according to ACOG. How much I don't know as mine isn't blurry. I have the ACOG TA31RCO and eye relief according to ACOG is 1.5 inches, but I have found that I can extend the eye relief out to 3" and more with no affect on how clear it looks. But I know that finding the proper eye relief for you can be different than the next person. I always try to roughly adjust the optic prior to putting a single round down range. I take a BUIS and mount it in front of the optic. Looking through the rear sight you can adjust the ACOG so it matches the alignment with the irons. You can then remove the BUIS if you aren't going to use it and you should be close when you go to the range. If this doesn't get you close to being on target and trying different eye relief distances doesn't clear the sight up it would be time to contact ACOG. Having different shooters try the same set up is great advice.
Link Posted: 11/18/2012 8:57:24 AM EST
The TA55's eye relief is pretty forgiving despite what Trijicon's official numbers say. I'd describe it as maybe a little shorter than a TA11, certainly nothing like the scope-biting TA31/01.

I think the problem could be in the ARMS mount on the riser setup.
Link Posted: 11/18/2012 9:07:08 AM EST

Originally Posted By Bizzarolibe:
Originally Posted By Indrid_Cold:
TA55A

Picture to clarify the mounting situation - the top half of the rail system extends over the AR-10 upper as part of the mounting process.



I'm not at all a fan of that mounting system you've got going on. That could very well be the problem. Have you tried shooting it with other optics to rule out the mount system as a possible problem?

Interesting - I just started thinking about this last night, and it very well could be the problem with the elevation issues, but it's not just up and down, it's also side to side.
Link Posted: 11/18/2012 9:07:49 AM EST

Originally Posted By madcratebuilder:
Then I noticed that the target seemed a little blurry. I took a look at one of the targets at 100y and saw that it was even blurrier - so much so that I almost couldn't see it.


Have another person look through the scope and see if the are getting a blurred image. It could be a bad scope.

Had my friend look at it at the range, and he agreed that it was blurry at distance.
Link Posted: 11/18/2012 9:22:02 AM EST
Ok, going to stop responding to individual posts and thank everyone here so far - this is really helpful. So far, I'm thinking I'm going to do the following...

1. Send the scope in. It's not just blurry on the sides, it's blurry all over the place and my friend has confirmed it was impossible to see targets at 100y.
2. Check out my handrail situation. I recognize the combination of the raised rail going over the top of the upper and the scope mount may just rise it too much.
3. Test all of my connections (barrel to upper, rail to upper, etc) to make sure they're secure.
4. Get some irons to test the zero-ability of the rifle itself.

Thanks again guys. I do appreciate this.
Link Posted: 11/18/2012 10:31:44 AM EST
[Last Edit: 11/18/2012 10:53:34 AM EST by Russ4777]
The centerline of the scope looks quite high above the barrel centerline. How is your cheekweld? Are you resting your chin on the stock to center your eye on the lens? You might want to get rid of what looks like a riser rail in you pic. Your lower step of your cheek bone should be resting on the buffer tube, not your chin. For a scope with a 2.2" eye relief it also looks like the scope is too far forward. With a .308 you won't want your nose touching the Charging Handle but you should be close. Are you shooting with the stock fully extended? If you are a somewhat normal sized guy you should most likely be doing that.

I agree with the poster above. Either use a laser boresighter stuffed in the bore or visually look through the bore at an identifable object 25-50 yards away. Adjust your scope reticle to be directly above that object equal to the distance between your rifle bore and the center of the scope. This should certainly get you on paper at 50. Fine tune the point of impact then pick a final zero distance and dial in your final zero. Get familiar with exterior ballistics and what the bullet trajectory does relative to the line of sight at different distances. Do not change ammo during this whole process. A change of ammo WILL change your zero regardless of the distance.
Link Posted: 11/18/2012 11:22:43 AM EST
I would start with a solid mount to your upper. I bet that fixes your problems. You wouldnt think it makes a difference but it really does.
Link Posted: 11/18/2012 5:00:39 PM EST
If the scope is blurry and others say it's blurry also, I'd bet it's the scope. Tighten this and tighten that doesn't matter if the scope is FUBAR. SEND IT BACK.
Link Posted: 11/20/2012 4:19:19 AM EST
Update in OP.
Link Posted: 11/20/2012 6:14:43 AM EST
[Last Edit: 11/20/2012 6:17:13 AM EST by NCHornet]
Looks like you found your problem. Congrats!!!!
I am sure Trijicon will take care of you.

I am leaving in an hour to sight in my TA31 and my TriPower on two different AR's. Hope I don't run into troubles like you did, lol!!! I am really surprised that more people aren't using the TRIPOWER. It is a awesome optic, I like it much more than my Aimpoint, and the price on these is far less than what the ACOG's go for.
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