View Full Version : MRO parallax remedy
Trying real hard to like the trijicon MRO. But my astigmatism forces me to use the rear back up sight with the red dot. Unfortunately, this causes a 6 inch parallax shift at 100 yards. I have considered switching the 1/3 lower mount for an absolute cowitness mount. Part of me thinks that this will work, part of me also says quit on the MRO and get a different optic. Perhaps a lpvo that will agree with my astigmatism better. This is currently mounted on a Colt 6720. General purpose use carbine for my children....
grizzlyblake
09-10-19, 07:52
I experienced the same thing. I ended up going with an Aimpoint T2. Much better in terms of parallax, and the dot is more crisp. I also have the astigmatism-type vision where most red dots starburst and double. The T2 is significantly better for me in that department.
AR15safespace.com was selling the T2s without mount for $535 and I got another vendor that I use to price match that for me. I just checked and now they are $599 without mount, but you can get it with a Reptilia lower 1/3 for $659. You have to add to cart to see those prices.
So your using the standard height rear sight in combination with a dot that’s not absolute? That makes no sense. The looking through a lower peep hole at a dot that is higher in the window could very well explain why you have a change in POI.
So your using the standard height rear sight in combination with a dot that’s not absolute? That makes no sense. The looking through a lower peep hole at a dot that is higher in the window could very well explain why you have a change in POI.
Bingo! That is why I am considering an absolute cowitness. For my other red dot sights that are 1/3 lower cowitness, the astigmatism and parallax shift is a non issue for my eyes. The MRO is a different story...
grizzlyblake
09-10-19, 09:09
The MRO is awful for parallax. I bought one and after playing with it for 5 minutes I returned it. Just sitting it on a fence post and looking at a tree 20ft away I could see huge shifts in the dot.
I also have the "astigmatism" that everyone talks about where most red dots look like starbursts or have some level of duplicating dot effect.
I ended up going with an Aimpoint T2 because the parallax issue is much improved, and the dot looks crisp for me which is unheard of in any other red dot ever.
A while back AR15safespace.com was selling T2s for $535. I couldn't get them to return an email so I got Primary Arms to match that price. I just checked them again and now they're $599 without mount once you add to your cart.
Depending on the severity of your astigmatism, a LPVO is the only slam dunk guarantee of no "Dot anomalies".
RKB Armory
09-10-19, 11:33
What about something like the Primary Arms 1x20 Prism Scope? It has an adjustable diopter, which might work well with your astigmatism.
Depending on the severity of your astigmatism, a LPVO is the only slam dunk guarantee of no "Dot anomalies".
Also a slam dunk guarantee for him losing the forgiving eyebox advantage of a RDS. I have been back and forth twice and prefer a squiggly dot over the LPVO on a rifle I might have to engage live targets at reasonable ranges with. A 6" shift at 100 yards means little to me.
Trying real hard to like the trijicon MRO. But my astigmatism forces me to use the rear back up sight with the red dot. Unfortunately, this causes a 6 inch parallax shift at 100 yards. I have considered switching the 1/3 lower mount for an absolute cowitness mount. Part of me thinks that this will work, part of me also says quit on the MRO and get a different optic. Perhaps a lpvo that will agree with my astigmatism better. This is currently mounted on a Colt 6720. General purpose use carbine for my children....
The absolute cowitness should work. Try that first.
Just placed an order for a full witness mount. Should make things better for me to zero the optic. The rifle is for my children. Their younger eyes may have no issue with the MRO. I will stick with my aimpoints.
RKB Armory
09-12-19, 07:31
Please, let us know if the absolute co-witness mount fixes the problem.
grizzlyblake
09-12-19, 07:37
How would changing the mount height of the optic fix the parallax issue in the optic itself?
I believe the optic does have a parallax issue. My problem is that my inability to see a definite red dot prevents zeroing. I have to use the rear aperture back up sight to make an actual usable dot. I have basically zeroed the sight in the lower 1/3 of the optic. Use the optic without the back up sight with the now fuzzy dot in the center of the optic? 6" shift in group size to the 2 O'Clock position....
I hope that the absolute cowitness mount will allow me to zero the optic and that my children don't have an astigmatism.
Why not just teach your kids to zero the rifle with the current setup?
mebiuspower
09-12-19, 12:55
Sell it and get an Eotech with the least amount of parallax compare to any other red dot sights.
How would changing the mount height of the optic fix the parallax issue in the optic itself?
Because parallax increases the further the dot or reticle is from the center of the viewing window.
I'd like to confirm that the OP's MRO exhibits a 6" shift from dot centered in the optic to being located in the lower 1/3 of the optic. Trijicon clearly states on their website, "Like all reflex-style optics, the Trijicon MRO is parallax-free when the dot and target are reasonably well centered in the optic's field-of-view, but when the reticle and target are substantially off-axis, there will be some parallax. The off-axis parallax performance of the MRO meets or exceeds that of other reflex sights of similar size.".
A six inch shift seems like a lot more than "some" parallax. I'm going to be zeroing an LPVO on Sunday, so I can take an MRO along to see if I'm able to duplicate your findings.
I'd like to confirm that the OP's MRO exhibits a 6" shift from dot centered in the optic to being located in the lower 1/3 of the optic. Trijicon clearly states on their website, "Like all reflex-style optics, the Trijicon MRO is parallax-free when the dot and target are reasonably well centered in the optic's field-of-view, but when the reticle and target are substantially off-axis, there will be some parallax. The off-axis parallax performance of the MRO meets or exceeds that of other reflex sights of similar size.".
A six inch shift seems like a lot more than "some" parallax. I'm going to be zeroing an LPVO on Sunday, so I can take an MRO along to see if I'm able to duplicate your findings.
Don’t forget to use your buis thats a different height then your rds.
My MRO mount is Absolute, but I've been running lower 1/3s for 8 years, so I should be able to approximate where the dot would be.
Other stuff came up today, but hope to make it to the outdoor range next weekend, if I don't take a day off during this week.
Sorry about the late updates. Had a family medical emergency that is slowly getting better.
But before people ended up in the hospital, I put a geissele absolute co witness on the 6720. The result was parallax shift was reduced enough while visualizing the dot through the rear aperture that I was able to finally zero the rifle. I am still not happy about the MRO. It fails to be the aimpoint that I should have duplicated. For now, my daughter likes it, so it remains.
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