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Thread: MRO Dot Size and Parallax?

  1. #1
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    MRO Dot Size and Parallax?

    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.

  2. #2
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    Quote Originally Posted by kerplode View Post
    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.
    Let's say you can hold 2 MOA and the rifle/ammo will shoot 2 MOA. IMO a 4 MOA 100 yard group from an improvised rest using a RDS is more than acceptable. What you need to do is shoot a 5-10 round group and adjust the scope to the center of the group. You are chasing your tail shooting 1 shot and adjusting. Dot size.. I don't think Trijicon ever put a 4 MOA dot in the MRO. I adjust my dot sights to float the target on top of the dot.

  3. #3
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    Yeah, even if your rifle is 4 MOA capable which it would be with ball ammo it's still a headshot @ 100 yards. It's a wild goose chase on a combat rifle.

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    But yeah the MRO is horrible compared to pretty much anything in regards to parallax.

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    Quote Originally Posted by grizzlyblake View Post
    But yeah the MRO is horrible compared to pretty much anything in regards to parallax.
    It is only around the outer edges that it really has a problem with parallax. If you have a proper shooting position on the stock and behind the glass it is not an issue just like a lpvo. If the aimpoint had a larger lense then it would be an issue as well.

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    Yeah that wasn't my experience at all. At 25yds very slight changes in cheek weld meant inches difference in POI.

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    Quote Originally Posted by grizzlyblake View Post
    Yeah that wasn't my experience at all. At 25yds very slight changes in cheek weld meant inches difference in POI.
    Green Eye Tactical did a big test on red dot parallax. MRO was pretty bad.

    Aso far as the dot size, do you have an aimpoint or other RDS with a 2 moa dot you could compare it to against a target at 100 yards?

  8. #8
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    Quote Originally Posted by grizzlyblake View Post
    Yeah that wasn't my experience at all. At 25yds very slight changes in cheek weld meant inches difference in POI.
    That is not my experience and most peoples experience that use current models that i have talked to or trained with. But hey we use it like a combat optic not a precision optic. My only issue is my astigmatism and if I dont wear glasses or contacts it being like a comet. Last time I used a eotech the outer ring was horrible. Was all pixelated.

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    I switched to an Aimpoint T2. Much more crisp dot without the starbursting or blurring, and almost no parallax to speak of I don't have any sort of hard numbers to share unfortunately.

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    Thanks for the replies, everyone!

    Next time I have a free afternoon, I'll take more ammo, go earlier in the day, and try again...This time being more careful about my cheek weld and eye alignment to minimize parallax. I'll also have to read that Green Eye Tactical test report. It sounds really interesting.

    All my other dot sights are older T1s and H1s, with an M3 thrown in for good measure. They're all 4MOA, but I think I'd still be a useful exercise to take one and do a dot size comparison.

    At the end of the day, though, I think you guys are right about not chasing it around and just getting it to print a 5 to 10 rnd group under the dot and calling it zeroed. I'm overthinking it and letting perfect be the enemy of good, or however that saying goes.

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