I was attempting to zero an MRO on my 11.5" SBR yesterday evening and I noticed something unexpected. As far as I know, the MRO specs a 2MOA dot. At 100 yards, however, it was covering nearly all of the center black bull on a B8 target. This is like 4+ MOA. It was dusk and I had the sight set on '2'. It was barely visible above ambient light level, so it wasn't blooming like it would be on a higher setting.

What gives? Am I misunderstanding how these dots are spec'd? I thought the spec measure was subtension (basically dot diameter = 2MOA) Is that not the case? Do I somehow have a 4MOA MRO despite the specs on the box?

I was also having much more trouble zeroing it than I have usually experienced with Aimpoints. I confirmed zero on the irons at 50yds, then set the dot on top of the front post. I moved the target to 100yds and my first pair was 1" low. Cool, right...2 clicks up and GTG. Well, I put on the two clicks (wow...close together and very quiet!) and fired another pair and they landed several inches high and left. WTF. Another pair went similarly askew in a different direction. Further adjustments just had me chasing it around.

I'm not that great of a shot, but I did my best smooth trigger pull and had the dot centered on the bull as the rounds broke. Maybe I wasn't as careful with cheek weld and centering the dot in the tube as I could have been between pairs. All the shots landed inside the dot, but I guess I expected better precision. Ammo was the IMI mk262 clone, which has been decent in my other rifles, although not sub-moa.

Could be the ammo, but does the MRO have exceptionally bad parallax when compared to a T1?

It got dark before I could screw with it much more so I'll have to try again next time I have a few free hours. Maybe I'll have better results, or just get the rounds landing as close to under the center of the dot as I can and call it good.