I hit up Vortex Chat Support. It looks like the the dot isn't designed for magnification...
But in a video by Travis Haley, it works just fine so IDK what is up.
I even sent Vortex the vid.
Talks about magnification at 2:30
My chat transcript with Vortex:
Chat started: 2019-03-21 03:30 PM UTC
(03:30:21 PM) Evan: Hi there.
I bought a Vortex 3x magnifier for my MRO and it makes the dot a slash. I think it has to do with the mount.
Do you guys have recommended MRO Mounts that will match your Magnifier?
(03:31:23 PM) Customer Service: Hello, sorry it is taking us a little while to respond, we will get back to you just as soon as we can.
(03:32:32 PM) *** Graham joined the chat ***
(03:32:36 PM) Graham: Hi Evan, thanks for reaching out!
(03:32:43 PM) Evan: of course you guys have great products
(03:33:29 PM) Graham: Do you know at all if you have any sort of astigmatism? Is the dot without the magnifier misshapen at all?
(03:33:57 PM) Evan: no astigmatism that I know of, Dot looks solid with no mag
(03:34:53 PM) Graham: Gotcha. The Magnifier shouldn't change the shape of the dot at all, but it will enlarge it. That is why I was asking about the astigmatism because if you even had a slight one it would then be magnified when paired up with the VMX-3T causing you not to see a perfect dot.
(03:35:15 PM) Graham: The MRO mounts will not match up with our VMX-3T magnifier. The only mounting option is the one that comes with it.
(03:35:28 PM) Graham: Have you adjusted the elevation and windage on the magnifier to align it with your optic?
(03:37:11 PM) Evan: I gave that a whirl but it still is a splotch slash. I am using a Kinetic Mount for the MRO and I think that it is a little out of alignment with the magnifier. I know people pair these two, I am just looking for info on the correct mount for MRO... I htink?
(03:38:01 PM) Evan: I put the magnifier behind my Holosun Dot and it comes out very clear. Perfect dot.
(03:38:04 PM) Graham: Hmmm. That I am not sure of. You are just going to want to make sure that whichever mount you use it will get you up to the proper lower 1/3 co-witness height of the VMX-3T.
(03:39:06 PM) Evan: yep. They are both 1/3. and I am using the shim
I tried a co-witness setup behind another MRO on a Geiselle mount and it still splotches. Not as bad, but not usable.
(03:39:34 PM) Graham: Give me one moment. I'm going to take a look into this and see if we have any recommendations for that.
(03:40:52 PM) Evan: Thanks!
(03:43:25 PM) Graham: Alright so it actually doesn't have anything to do with the mounting. It actually has to do with the design of the red dot.
(03:44:15 PM) Graham: The MRO has a short focal length and when paired with a magnifier will induce vertical parallax and cause you to see a slash. This is why we don't recommend pairing the VMX-3T magnifier with some of our tubular red dots that have short focal lengths.
(03:44:36 PM) Evan: hmmmmm...
(03:44:54 PM) Evan: but others are having success with the MRO and the vortex...
(03:45:09 PM) Evan: just on amazon reviews for starters:
(03:45:09 PM) Evan:
https://www.amazon.com/Vortex-Optic...=B00BQWTC14&psc=1&refRID=FEKTRHT3Z0KVGHC2NPYS
(03:45:47 PM) Graham: And they might but it is not something that we would recommend pairing together.
(03:46:25 PM) Evan: well... then I am looking at sending it back, i guess. I still feel pretty sure that it could be the missmatched mount, htough
(03:47:15 PM) Evan: this is a video from Travis Haley with the two paired:
(03:47:15 PM) Evan:
(03:47:22 PM) Graham: The mount is not going to change the focal length of the red dot. Even if for some reason you can clear up the slash, you will still risk experiencing vertical parallax.
(03:47:25 PM) Evan: I started it when he shows the vortex
(03:47:40 PM) Evan: hmmm...
(03:47:42 PM) Evan: bummer
(03:48:50 PM) Graham: Yeah and actually the other optics he is showing in that video we do not recommend pairing it up with such as the Aimpoint T1/T2.
(03:49:11 PM) Evan: so... how does that work?
(03:49:13 PM) Evan: luck?
(03:51:18 PM) Graham: Some people run it and again do not have the slash, but we found in our testing that pairing up a short focal length red dot with a magnifier will induce vertical parallax. This is something that we do not recommend doing and want to make sure that it is clear to the end user that this is something that they can experience causing improper shot placement.
(03:51:40 PM) Evan: well bummer.
(03:52:55 PM) Graham: If you have any other questions regarding this, please let me know!
(03:53:22 PM) Evan: It sounds like I am out of luck
(03:53:56 PM) Graham: Yeah unfortunately those red dots are just not meant to be paired with magnifiers.
(03:54:12 PM) Evan: that is major bummer
(03:54:18 PM) Evan: well thanks for you help
(03:54:31 PM) Graham: Anytime! If I can help with anything else, let me know.