I have a Colt LE6940 (integral top rail) and an EOTech EXPS2 Holographic Sight with a EOTech 3X Magnifier (optics came as a set). I bought the rifle and optics new last year and I've shot very few rounds with it - maybe 200 or 300 rounds or so. Whenever I went to my range, the wind was pretty strong so I didn't expect sighting to be spot-on but I did notice a potential problem. Today I went to the range and, for the first time, there was almost no wind so I could finally see if there was a problem or if it was just a wind problem before.
A couple weeks ago, I roughly sighted in the rifle at 25 yards knowing where the POI should be for a final sighting at 50 yards. When that was done and the shots were virtually in the same hole, I moved to the 50 yard range. To my surprise, POI was a couple inches to the right. But on that day, there were winds of about 10 MPH to 15 MPH or so and I didn't give it much thought. I zeroed for 50 yards and called it a day. (That should just about zero me at 200 yards too.)
Today I went back to the 50 yard range to check things because I had dismounted and re-mounted the sight to clean the rifle since the last time I was at the range. If I remember correctly, that could throw POI off by 1 or 2 MOA according to EOTech. The rifle was shooting about 1 - 1.5" inch or so to the left now and I assumed that was just from remounting the optic. So I got it zeroed again so the shots were dead on and then moved to the 100 yard range where I expected POI to be about 1.6 high or so. Elevation was good and as I expected but hits were about 1.5" to the right.
After a little thought and after talking to my son who is a precision long-range shooter and ex-Marine (I know - there are no ex-Marines! ), I realized that this could happen if the optic was aligned at a slight angle on the horizontal axis. I hope that makes sense. If that is the case, then I could expect to always see impacts to the right as I move out to longer ranges if my thinking is correct.
Has anyone seen this before and, if so, what's the fix? If the EOTech is at an angle, is there a way to adjust it? (BTW, my EOTech is quick-release.)
Also, I should mention that I didn't change any adjustments until sighting the rifle. EOTech says the optic is set at mechanical zero from the factory and not to mess with that before mounting it to the rifle so I didn't. I just thought I would mention that. I'm not even sure if that could cause the problem I'm seeing if I had messed with it but I didn't anyway. I mention that because, if it could cause the problem I'm seeing, I could set the optic to mechanical zero again and start over but that shouldn't be necessary if it was zeroed from the factory.
(I would appreciate it if nobody gets into what the best range to sight in is. That's an entirely different issue and it would side-track my question. )
Also, keep in mind that the Colt LE6940 has an integral rail that is part of the upper so there's no issue of the rail being mounted incorrectly.
A couple weeks ago, I roughly sighted in the rifle at 25 yards knowing where the POI should be for a final sighting at 50 yards. When that was done and the shots were virtually in the same hole, I moved to the 50 yard range. To my surprise, POI was a couple inches to the right. But on that day, there were winds of about 10 MPH to 15 MPH or so and I didn't give it much thought. I zeroed for 50 yards and called it a day. (That should just about zero me at 200 yards too.)
Today I went back to the 50 yard range to check things because I had dismounted and re-mounted the sight to clean the rifle since the last time I was at the range. If I remember correctly, that could throw POI off by 1 or 2 MOA according to EOTech. The rifle was shooting about 1 - 1.5" inch or so to the left now and I assumed that was just from remounting the optic. So I got it zeroed again so the shots were dead on and then moved to the 100 yard range where I expected POI to be about 1.6 high or so. Elevation was good and as I expected but hits were about 1.5" to the right.
After a little thought and after talking to my son who is a precision long-range shooter and ex-Marine (I know - there are no ex-Marines! ), I realized that this could happen if the optic was aligned at a slight angle on the horizontal axis. I hope that makes sense. If that is the case, then I could expect to always see impacts to the right as I move out to longer ranges if my thinking is correct.
Has anyone seen this before and, if so, what's the fix? If the EOTech is at an angle, is there a way to adjust it? (BTW, my EOTech is quick-release.)
Also, I should mention that I didn't change any adjustments until sighting the rifle. EOTech says the optic is set at mechanical zero from the factory and not to mess with that before mounting it to the rifle so I didn't. I just thought I would mention that. I'm not even sure if that could cause the problem I'm seeing if I had messed with it but I didn't anyway. I mention that because, if it could cause the problem I'm seeing, I could set the optic to mechanical zero again and start over but that shouldn't be necessary if it was zeroed from the factory.
(I would appreciate it if nobody gets into what the best range to sight in is. That's an entirely different issue and it would side-track my question. )
Also, keep in mind that the Colt LE6940 has an integral rail that is part of the upper so there's no issue of the rail being mounted incorrectly.
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