I am running a BCM 16 inch mid length with a BCM lower and I just bought a Eotech 512 to run as my red dot sight. Once mounted, I went out to zero it. I started by comfirming that the iron sights were zeroed at 25 m. Then, I started dailing in the Eotech shooting from a bench at a eotech 25m zeroing target I got off the net and I was quickly able to get zeroed at 25m.
I then moved to 50m and again confirmed the zero with my irons, which were again good to go. Then I tried the eotech, which i found to be a little high, but not enough to make any adjustments.
Next, I moved out to 100m, and again confirmed my irons, which were about 1.5 inches high of point of aim. I didn't make any adjustments to my irons because I didn't think that was bad for 100m. I then gave my eotech a try and found that they were 3.5 inches high of point of aim at 100m.
So, my question is, am I doing something wrong? Shouldn't the eotech be a little closer than 3.5inches from point of aim at 100m? Should I make the adjustments to get it closer at 100m, which i think will through off my zeroing at 25 and 50m, or should I just leave it the way it is and know that I will have to aim lower when I get out to these distances?