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Posted: 5/15/2010 5:20:27 PM EDT
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I imagine this has been covered before but I did do a search and couldn't find anything.
I received my very first ACOG today from a purchase through the EE. It is a TA31F. My first impression is I am very impressed with the scopes clarity, the reticle, and the "tough" feel of the ACOG. I was attempting to zero at 100 meters today and ran into a problem however. This was with 55gr M193. My first two shots were maybe 5 inches left and 4 inches high 3"-4" spread. I moved 10 clicks right, 2 shots, centered on windage but 4 inches high, <1" spread. 5 clicks down, 2 shots, and I'm 2" high and a hair left, <1" spread. Another 5 clicks down; 2 shots, now things get weird. I have one round 4 o'clock of target 4" off; other round is 7 o'clock of target 8" off. I brushed it off as two bad pulls and didn't adjust any. Two more shots. One is totally off target; the other is 8 o'clock 10" off. Two more rounds, one round is 5 o'clock 5" off; other is 6 o'clock 7" off. So now I went from good tight groups steadily moving into zero to now scattering shots. I stopped shooting as something was obviously wrong and no reason to waste ammo. I don't know if maybe it was me and eye fatigue or the scope. The ACOG is sitting on a TA51 mount and was already attached when I got it. I didn't mess with the screws attaching the ACOG to the TA51 except for briefly checking their tightness. They seemed tight but I didn't twist too hard. I wasn't sure what to do with the screws that attach the TA51 to the flattop rail. I hand tightened them and then another 1/2 to 3/4 turn with a screwdriver. Not sure if that was too tight maybe? It would almost seem to me that the scope has recoiled itself loose somehow since I was getting good groups and movement early on and then all of a sudden it started scattering. The barrel had ample time to cool as we took 3 minutes or so to walk to and analyze the target between groups. If that is at all understandable let me know what you think.  Thanks.
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Two things...
M193 is maybe 2-3 MOA ammo at best. If the rifle isn't grouping, regardless of zeroing, then I'd first look at ammo, then make sure the scope and mount are in good shape, then make sure the barrel's not loose in the upper. In other words, look at the whole system a piece at a time. And look at the easy stuff first. When I zero, I work on either windage or elevation at a time. I don't try to "move it down two and over 3". Get one right, then work on the other. Don't fiddle with both at the same time. |
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Thanks for the reply.
I realize M193 isn't the best ammo. I figured I'd zero with it though since it matches the 55gr BAC. I also only do either windage or elevation at a time; not both. I just thought it was strange how I was getting good movement and groups and then suddenly it was all over the place. I'd have to look at my target to be sure but I got to thinking. While waiting for my scope to arrive I did a google search and read where you are supposed to tap/smack the scope after an adjustment for some reason? Now that I think about it, I did tap it on the first 2 or 3 groups and then blew it off and quit hitting it. That might have been when the groups went crazy. If my first round was resetting the reticle through recoil and my second round was following the adjustments. Since I only fired 2 rounds per groups I wouldn't know. I should've fired at least 3. Have you heard anything about hitting the ACOG to reset the reticle? I'm going to give it another try tomorrow. |
| Same here, when I do adjustments when sighting in. I shoot 20 rds at a time then adjust. If you only fire 2 shots at a time, you leave a ton of room for error. Slight change in wind (if outdoors), slight trigger jerk, fatigue of any type... Putting more shots down range will show more consistancy in what you need to change if anything. |
| Definitely would use more than 2 shot groups. Secondly were you following the manual? If you dont have one you can download it at trijicons site. Also after making an adjustment you should smack the optic hard as it helps the prism inside. Manual actually recommends firing spoiler round after adjustment as the recoil is needed to set the adjustment. Its not your Dads old weaver and uses different technology. Hope it all works out for you. I love my ACOG. |
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Quoted:
I imagine this has been covered before but I did do a search and couldn't find anything. I received my very first ACOG today from a purchase through the EE. It is a TA31F. My first impression is I am very impressed with the scopes clarity, the reticle, and the "tough" feel of the ACOG. I was attempting to zero at 100 meters today and ran into a problem however. This was with 55gr M193. My first two shots were maybe 5 inches left and 4 inches high 3"-4" spread. I moved 10 clicks right, 2 shots, centered on windage but 4 inches high, <1" spread. 5 clicks down, 2 shots, and I'm 2" high and a hair left, <1" spread. Another 5 clicks down; 2 shots, now things get weird. I have one round 4 o'clock of target 4" off; other round is 7 o'clock of target 8" off. I brushed it off as two bad pulls and didn't adjust any. Two more shots. One is totally off target; the other is 8 o'clock 10" off. Two more rounds, one round is 5 o'clock 5" off; other is 6 o'clock 7" off. So now I went from good tight groups steadily moving into zero to now scattering shots. I stopped shooting as something was obviously wrong and no reason to waste ammo. I don't know if maybe it was me and eye fatigue or the scope. The ACOG is sitting on a TA51 mount and was already attached when I got it. I didn't mess with the screws attaching the ACOG to the TA51 except for briefly checking their tightness. They seemed tight but I didn't twist too hard. I wasn't sure what to do with the screws that attach the TA51 to the flattop rail. I hand tightened them and then another 1/2 to 3/4 turn with a screwdriver. Not sure if that was too tight maybe? It would almost seem to me that the scope has recoiled itself loose somehow since I was getting good groups and movement early on and then all of a sudden it started scattering. The barrel had ample time to cool as we took 3 minutes or so to walk to and analyze the target between groups. If that is at all understandable let me know what you think. Thanks.When you mount your sight on the rail, push it forward to remove the slack prior to tightening the the knobs. Tighten to finger tight, than apply a quarter turn with a quarter (or screw driver). After each adjustment, slap the windage and elevation knobs to jar the sight and ensure the turret and elevating mechanism moves. |
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