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Posted: 1/24/2005 2:09:39 PM EDT
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Just a quick question to see if any TA31 users had ever encountered parallax issues with the ACOG while doing dynamic shooting from a fighting stance - either stationary or while moving. I'd been playing "show & tell" on the range the other day and someone opened up my stock to one notch past where I usually run it for this type of shooting. I didn't notice the change and made several runs at the same set of targets with really horrible results. I finally slowed down to a glacial pace and noticed that even though I had brought the rifle up as I normally would, my nose wasn't on the charging handle. I ran the stock in a notch and problem solved. With the TA11, I still had a perfectly clear and usable sight picture but my rounds were impacting 6-7" below the point of aim. I'm thinking parallax was the issue and also thinking that the TA31 wouldn't have the same problem because the fact you were pushing the eye relief limits would be more apparent. It also makes me wonder how many other times in the past when I thought I had a perfect sight picture but rounds weren't on target I was actually just moving my head too much and didn't notice it. Thought I would throw this out there for feedback from others who used the optic for 3-gun/IPSC stye shooting. |
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You will get POI shift from inconsistent eye relief. The POI with my TA-11 will shift one full minute vertical and 1/2 MOA windage when shooting prone with a bipod vs. shooting prone with a sling (FF forend). As you noted, the TA-11 is foregiving enough in eye relief that you do need to discipline yourself on cheekweld. Luck, SD |
Were you doing any shooting from your back or other unconventional positions where you were pushing the eye relief limits more than you usually might? |
I was still upright, but with no cheek weld and my shoulder off the stock, similar to this, but not pictured: [ link to LARGER image ] |
| Consistent head position is critical out to 100 yards, sometimes even more, with ACOGs. It is only flagrantly apparent when you are shooting fast on multiple targets and might not have the most solid cheekweld. The close ranges, from 20 50 yards, can be particularly annoying as the target/reticle picture is so good. For stationary shooting, even unsupported, most will unconsciously take enough time to center the reticle in the field of view, which takes care of most of the issue (your 10-12" plate rule, Zak), but the ACOGs are so easy to see through that when you try to go fast you get an acceptable sight picture and fire long before that fine adjustment takes place. Only cure I know is lots of good practice at a slow enough speed to gain the requisite muscle memory. Then you can do it on the fly without the secondary adjustment. |
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This is a good thread. It's got me rethinking the ACOG- I'd pretty much settled on getting a 11, but now I'm not sure the extra eye relief over the 31 is worth it if the POI can be so far off; Like Bartholomew Roberts is suggesting, you pretty much would have to have a more consistent cheek weld with the 31. I'm wanting to go with whatever one is better for CQB; damnit just when I got something figured out something like this comes along and I gotta rethink it all. Wish I could afford to "get both" 
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